LPC Bituminous Mixtures Design Guide …aapaq.org › MC2012 › PAB ›...

LPC Bituminous Mixtures Design Guide

The RST Working Group "Design of bituminous mixtures "

Under the supervision of

Jean-Luc DELORME,

Chantal de la ROCHE,

Louisette WENDLING

September 2007

Laboratoire Central des Ponts et Chaussées 58, bd Lefebvre, F 75732 Paris Cedex 15

Jean-Luc DELORME Laboratoire Régional des Ponts et Chaussées de l’Est Parisien Chantal de la ROCHE Laboratoire Central des Ponts et Chaussées Louisette WENDLING Laboratoire Régional des Ponts et Chaussées d’Autun

This report was compiled from the documents produced by and with the participation of the "Design of bituminous mixtures" working group, coordinated by Mr. Jean-Luc DELORME. Below is the list of working group members: Yves BROSSEAUD, Laboratoire Central des Ponts et Chaussées Yves GANGA, Laboratoire Régional des Ponts et Chaussées de Clermont-Ferrand René HIERNAUX, Laboratoire Régional des Ponts et Chaussées de Saint-Quentin Jean-François LAFON, Laboratoire Régional des Ponts et Chaussées de Toulouse Francis MOUTIER, Laboratoire Central des Ponts et Chaussées Claude ROGER, Laboratoire Régional des Ponts et Chaussées de Strasbourg Patrick VAN GREVENYNGHE, Laboratoire Régional des Ponts et Chaussées – d’ Aix-en-Provence

Also providing valuable assistance with this publication were: Chantal de la ROCHE, Laboratoire Central des Ponts et Chaussées Florence PERNOT-MOREAU, Laboratoire Régional des Ponts et Chaussées de l’Est Parisien François TRAVERS, Laboratoire Central des Ponts et Chaussées Louisette WENDLING, Laboratoire Régional des Ponts et Chaussées d’Autun Nicole VERCHERE, Laboratoire Régional des Ponts et Chaussées de l’Est Parisien Preface contributed by: Jean-Michel PIAU, Technical Director for Pavements and Road Safety, Laboratoire Central des Ponts et Chaussées

LPC Bituminous Mixtures Design Guide – Preface –

–3 –

Preface

LPC Bituminous mixtures Design Guide

Jean-Michel PIAU

This guide is intended to collate and set forth the knowledge accumulated by France's Ministry of Public Works' Scientific and Technical Network (RST) in the field of designing hot bituminous mixtures. It provides a description of:

⎯ the bituminous mixtures design method used by RST; and ⎯ the rules of practice and expertise introduced in asphalt mix design studies,

for the purpose of efficiently obtaining materials capable of meeting a series of predefined specifications.

This document has been compiled with an educational aim of transferring knowledge and standardizing methods currently applied within the various Ponts et Chaussées laboratories. It would be beneficial however to expand the document scope over the near term by contributions from the world of industry to give rise to the publication of a "French method for road material design". This effort would allow covering the entire range of techniques implemented throughout France capable of being shared among our European and international partners. We felt it appropriate to use this guide's introductory section to recall the main objectives inherent in bituminous mixtures design methods and then to explain the predominant constituents based of a streamlined formulation, making it more straightforward to grasp long and complex processes that often imply developing such methods. It then becomes easier to understand the diversity of methods in use across the world. Highlighting the key stakes involved and the breadth of this topic still to be explored also serves to justify the permanence of research resources allocated to improving and optimizing mix design methods. Along the same lines, a number of preliminary considerations will be provided below on another aspect of this "bituminous mixtures design" focus; these concern more specifically the mix design studies actually being conducted.


–4 –

The objectives behind a road material design method in the laboratory are basically of three types. The impetus lies in deriving and proposing materials that are:

⎯ capable of being successfully implemented on a jobsite, ⎯ capable of resisting the loads induced from the rest of the project works, ⎯ capable of satisfying the structural durability or wearing requirements of

pavements, as specified by project developers. The quality and relevance of asphalt mix design methods exert a strong influence on user safety, as well as on the durability and maintenance costs associated with the particular infrastructure. Yet these methods remain valuable tools for innovation, by virtue of providing guides for the development and improvement of experimental materials and creating the means for evaluating performance at an early stage and at relatively low cost. Generating a mix design method entails a long and complex process that requires considerable back-and-forth between field and laboratory over an extended period of time; broadly speaking, this approach is more heavily dependent upon the (cultural) context of pavement design methods and product standardization / classification. Bituminous mixtures design methods rely upon three cornerstones, all highly correlated and interdependent. The first pertains to the set P of physical, chemical and mechanical properties considered as necessary and adequate for determining the aptitude of constituents and mixes to form proper road materials. The second cornerstone is the set E of tests and testing methods used in order to measure these properties. The third cornerstone is the set V of threshold values to be reached or not exceeded, depending on the properties required of the project structure over its life cycle; these are to be included in the specifications issued by project developers. Among the first set P , it is important to distinguish between magnitudes Pc applicable to constituents and magnitudes Pm applicable to mixes. Within the latter category, distinction must also be drawn between magnitudes Pv of the volumetric type, such as the concentration modulus and void content, and performance-related mechanical or physical magnitudes ,Pf of the empirical or intrinsic type, such as rutting resistance, fatigue resistance and stiffness modulus. Historically speaking, these methods were typically based on Pc and Pv properties, i.e. more likely to yield direct and ready-to-use design rules; they are referred to as " compositional recipe" guides. Subsequent methods sought to integrate, without completely overlooking the initial approaches, an increasing number of performance-related magnitudes, closer to properties that were directly representative of material behavior within structures, yet more complicated to assess and incorporate into the actual design. The rising importance assigned today to material recycling or reuse techniques in road construction and maintenance, which has served to broaden component diversity, merely strengthens the need for performance-related design methods that focus directly on the bituminous mixtures.


–5 –

The selection of tests and testing methods E associated with parameter measurements P again offers many degrees of freedom in determining design methods. This trend is even more pronounced given that set E also includes the choice of specimen preparation methods, which often differ from one country to the next1. It should nonetheless be pointed out that for properties P relating to European standardization, a major step forward has recently been taken by mandating a single type of test and testing method2. The third cornerstone comprises the ranges of acceptable values V associated with variables P , given the selected tests E and the particular use sought for the materials. Making such a selection engenders considerable reflection, which typically invokes a preexisting reference derived over time and based on a comparison drawn between field observations and design methods. For standardized materials, set V is organized by material category, which serves to combine the target specifications for the variables found in set P homogeneously and consistently. The application of corresponding product-based standards then enables streamlining project developer specifications. Let's also point out herein that depending upon the precise needs expressed in the asphalt mix design3, several levels of total or partial method application are generally defined; these would correspond with the implementation of subsets { }',',' VEP composed within the { }VEP ,, triad.

Mix design studies lie within the scope framed by the methods actually used, which tend to focus on generating materials that satisfy the specifications stipulated by the project developer, through manipulating design variables under supervision of the project's general contractor. Yet many other situations could also warrant the creation of design test specimens. When designing a new hot bituminous mix, set F containing designer degrees of freedom usually pertains to:

⎯ the broad choices for the mix's mineral phase (filler, fines, sands, aggregates), depending on project constraints and location;

⎯ choice of binder (type, hardness); ⎯ the eventual introduction of admixtures (e.g. enhancers); ⎯ choice of particle size distribution; and ⎯ binder content.

In symbolic terms, a mix design problem entails solving the following program:

1 Example: Depending on the country, distinction can be drawn from among four major specimen

preparation methods; using a plate compactor, compaction with the gyratory shear press, compaction by impact (rammer) or vibration.

2 Beyond a certain number of properties, for which the corresponding tests are deemed equivalent. 3 Design of a new material, periodic formula verification, …


–6 –

Find F such that VEFP ∈),( with:

F = Design parameter values E = The tests and test methods employed (including specimen preparation)V = Intervals (potentially semi-infinite) of the required performance values

),( EFP = Material responses, as derived according to values F with tests E

The designer's craftsmanship enters into play through minimizing the number of laboratory tests (i.e. the number of designs undergoing testing), thereby yielding a solution to this problem. Designer expertise is often primarily implicit, based on extensive personal experience and in-depth knowledge of road materials and of their sensitivity, in qualitative (and sometimes quantitative) terms, to design parameters. Yet most of these rules, some of which had been intentionally built on the basis of multi-faceted experimental programs4, are now understood and help stimulate learning of the mix designer's trade. The core of the present document will lay out these rules in detail. In contrast, the actual techniques used for solving asphalt mix design problems, as regards the current discussion, and introduced by material designers have for the most part remained implicit. In returning to the overview presented above, it can simply be stated that approaches rely for the most part on iterative "progressive" methods built from a qualitative5, or in

some instances quantitative, knowledge of the sensitivity matrix F

EFP∂

∂ ),( , thereby

ensuring a suitable correction of design parameters from the standpoint of narrowing the discrepancy between the current ),( EFP value and the target interval V . If need be, this approach could be adopted when developing computer-aided design software.

4 Example: The RST study entitled "Multi-year Fatigue Plan for Bituminous mixtures". 5 A qualitative knowledge of the sensitivity matrix

FP

∂∂

entails knowing the algebraic sign of matrix

components and in some instances more than their simple orders of magnitude.

–7 –

Table of Contents

PREFACE ........................................................................................................................... 3

TABLE OF ILLUSTRATIONS........................................................................................... 11

RÉSUMÉ........................................................................................................................... 14

ABSTRACT....................................................................................................................... 15

1 GENERAL REMARKS – BASES OF THE METHOD........................................... 17

1.1 Introduction............................................................................................................ 17 1.1.1 The various mix design approaches.................................................................... 17 1.1.2 Type testing procedures applied in France ......................................................... 19

1.2 Presentation of this document ............................................................................... 19

1.3 Test protocols in application .................................................................................. 20 1.3.1 Gyratory compactor ............................................................................................. 21 1.3.2 Water resistance sensitivity................................................................................. 22 1.3.3 The wheel tracking test (large device)................................................................. 23 1.3.4 Stiffness testing ................................................................................................... 23 1.3.5 Fatigue resistance ............................................................................................... 25

1.4 General remarks on bituminous mix components ................................................. 25 1.4.1 Aggregates .......................................................................................................... 26 1.4.2 Binder .................................................................................................................. 27 1.4.3 Additives.............................................................................................................. 30

1.5 Useful definitions and relations for type testing ..................................................... 33 1.5.1 Binder content ..................................................................................................... 34 1.5.2 Richness modulus K............................................................................................ 34 1.5.3 Percentage of voids or compacity ....................................................................... 35

2 TYPE TESTING OF BITUMINOUS MIXTURES ................................................... 41

2.1 Prescription relative to mix components................................................................ 42 2.1.1 Specifications regarding added fillers................................................................. 42 2.1.2 Specifications regarding fillers contained in the mixture .................................... 43 2.1.3 Specifications regarding fine aggregates or all-in aggregate (0/4, 0/6)............... 43 2.1.4 Specifications regarding coarse aggregates ....................................................... 44 2.1.5 Specifications regarding additives....................................................................... 47 2.1.6 Specifications regarding binders ......................................................................... 48 2.1.7 Specifications regarding reclaimed asphalt......................................................... 49

2.2 Specifications regarding mixture composition ....................................................... 51 2.2.1 Grading................................................................................................................ 51 2.2.2 Binder content and Richness Modulus................................................................ 52

–8 –

2.3 Preparation of test specimens ............................................................................... 53 2.3.1 Density measurements........................................................................................ 53 2.3.2 Procedure for reheating and incorporating mix reclaimed asphalts .................... 54 2.3.3 Mixing .................................................................................................................. 55 2.3.4 Compaction of test specimens ............................................................................ 55 2.3.5 Test specimen sawing and bonding .................................................................... 55 2.3.6 Test specimen conservation................................................................................ 55 2.3.7 Test specimen void percentage .......................................................................... 56

2.4 Execution of type testing ....................................................................................... 56 2.4.1 Choice of test typing level ................................................................................... 56 2.4.2 Level 1................................................................................................................. 57 2.4.3 Level 2................................................................................................................. 60 2.4.4 Level 3................................................................................................................. 60 2.4.5 Level 4................................................................................................................. 61 2.4.6 Additional tests .................................................................................................... 62

2.5 Formula verification ............................................................................................... 62

2.6 Type testing procedure length and required quantity of materials......................... 63

2.7 Summary of test characteristics and methods....................................................... 64 2.7.1 Asphalt mixes ...................................................................................................... 64 2.7.2 Very thin asphalt concretes ................................................................................. 66 2.7.3 Soft asphalt concretes......................................................................................... 67 2.7.4 Hot Rolled Asphalt............................................................................................... 68 2.7.5 Stone Mastic Asphalt........................................................................................... 69 2.7.6 Porous Asphalt .................................................................................................... 70

3 MIX DESIGN PROCEDURE.................................................................................. 73

3.1 Component selection............................................................................................. 73 3.1.1 Aggregates .......................................................................................................... 73 3.1.2 Binder .................................................................................................................. 79 3.1.3 Additives.............................................................................................................. 81

3.2 Relationships between binder properties and mix properties................................ 83 3.2.1 Penetrability and ring and ball temperature......................................................... 83 3.2.2 The SHRP criteria ............................................................................................... 83 3.2.3 Origin of the bitumen ........................................................................................... 84

3.3 Initial composition by type of material.................................................................... 85 3.3.1 Asphalt Concretes for base course – Grave-Bitume AC-GB and High

Modulus AC-EME............................................................................................... 85 3.3.2 Thick layer mixtures for surface or binder course – AC-BBSG, AC-BBS,

AC-BBME ............................................................................................................ 90 3.3.3 Porous asphalt mixes – PA-BBDr........................................................................ 92 3.3.4 Thin asphalt mixes – AC-BBM, BBTM and mixes for UTLAC (BBUM) ............... 95 3.3.5 Stone Mastic Asphalt - SMA................................................................................ 98

3.4 Composition adjustments ...................................................................................... 99 3.4.1 Effect of mix variables (general remarks) .......................................................... 100 3.4.2 Effect of dimension D ........................................................................................ 100 3.4.3 Effect of granular proportions ............................................................................ 100

–9 –

3.4.4 Discontinuity ...................................................................................................... 100 3.4.5 Incorporation of rounded particle aggregate ..................................................... 101 3.4.6 Percentage of fillers........................................................................................... 101 3.4.7 Percentage of bitumen ...................................................................................... 101

3.5 Gyratory Compactor compactibility study ............................................................ 101 3.5.1 General remarks................................................................................................ 101 3.5.2 Percentage of voids vs. number of gyrations .................................................... 102 3.5.3 Percentage of voids at a given number of gyrations ......................................... 103 3.5.4 Percentage of voids at 10 gyrations: v10............................................................ 104 3.5.5 Percentage of voids at 1 gyration: v1................................................................. 104 3.5.6 Slope K1............................................................................................................. 104 3.5.7 Pseudo shear stress τ ....................................................................................... 105 3.5.8 Test precision .................................................................................................... 106 3.5.9 Correction of mix composition ........................................................................... 106

3.6 Mix performance.................................................................................................. 110 3.6.1 Resistance to permanent deformation on the LPC Wheel Tracking Tester ...... 110 3.6.2 The Duriez test (Method B of EN 12697-12) ..................................................... 114 3.6.3 Stiffness modulus .............................................................................................. 116 3.6.4 Fatigue .............................................................................................................. 121 3.6.5 Texture .............................................................................................................. 122 3.6.6 Ancillary tests .................................................................................................... 123

3.7 Practitioners' advice ............................................................................................ 124 3.7.1 Effect of mix design factors – Summary............................................................ 124 3.7.2 Practical tips for the mix designer ..................................................................... 125

4 RELATIONSHIPS BETWEEN LABORATORY AND FIELD RESULTS ............ 127

4.1 Percentage of voids measured with the Gyratory Compactor (GC) .................... 127 4.1.1 Experimental objective ...................................................................................... 127 4.1.2 Results .............................................................................................................. 128 4.1.3 Comments ......................................................................................................... 131

4.2 Large device wheel tracking test ........................................................................ 132 4.2.1 The studies conducted in France ...................................................................... 132 4.2.2 Colorado study .................................................................................................. 134 4.2.3 Ranking of mix rutting behavior ......................................................................... 135

4.3 Stiffness modulus test ......................................................................................... 136 4.3.1 Experimental objective and procedure .............................................................. 136 4.3.2 Results .............................................................................................................. 137

4.4 Fatigue test.......................................................................................................... 140 4.4.1 Experimental objective and procedure .............................................................. 140 4.4.2 Results obtained................................................................................................ 140

4.5 Synthesis of the relationships between laboratory and field results .................... 142

5 CONCLUSION .................................................................................................... 143 Bibliography..................................................................................................................... 144 Appendix A: List of normative references required for the type testing phase ................ 149

–10 –

Appendix B: EN testing standards - EN 12697 series: "Asphalt mixes" Use recommendations................................................................................ 154

Appendix C: Equivalence table between TLext and Bint.................................................... 159 Appendix D: Main test precisions .................................................................................... 160 Appendix E Summary table – Specifications and recommendations for each type

of material................................................................................................... 162 APPENDIX F ................................................................................................................... 164 Appendix G Glossary ...................................................................................................... 175 Index .......................................................................................................................... 197

–11 –

Table of illustrations Figure 1: Gyratory Compactor – MLPC Type 2 ....................................................... 21 Figure 2: Gyratory Compactor – MLPC Type 3 ....................................................... 21 Figure 3: Large-device wheel tracking test ............................................................... 23 Figure 4: Detail of the rut depth measurement ......................................................... 23 Figure 5: Complex modulus testing machine - MLPC 3MC ..................................... 24 Figure 6: Adjustment of the displacement sensor..................................................... 24 Figure 7: Rheologically-controlled testing machine .................................................. 24 Figure 8: Specimen set-up........................................................................................ 24 Figure 9: Fatigue test in 2-point bending on trapezoidal specimens......................... 25 Figure 10: View of quarry face.................................................................................. 26 Figure 11: Screening-crushing.................................................................................. 26 Figure 12: Penetrability test ...................................................................................... 30 Figure 13: Ring and ball temperature test ................................................................ 30 Figure 14: Example of extraction on Trinidad Lake (Venezuela) .............................. 32 Figure 15 : Examples of colored asphalt mixes ........................................................ 33 Figure 16: Volumetric approach to developing an asphalt mix ................................. 36 Figure 17: Connecting, non-connecting and occluded voids .................................... 37 Figure 18: Summary diagram of the various type testing levels ............................... 57 Figure 19: Small-scale rutting tester model operating in air...................................... 70 Figure 20: Cross-section of a Grave-Bitume AC-GB mix.......................................... 85 Figure 21: Cross-section of a AC-BBSG ((Asphalt Concrete Béton

Bitumineux Semi-Granular)) .................................................................... 90 Figure 22: Surface appearance of a AC-BBSG (Asphalt Concrete Béton

Bitumineux Semi-Granular) ..................................................................... 90 Figure 23: Cross-section of a Porous Asphalt .......................................................... 92 Figure 24: Surface appearance of a Porous Asphalt (PA-BBDr) .............................. 92 Figure 25: Cross-section of a Thin Layer Asphalt Concrete (AC-BBM) .................... 95 Figure 26: Surface appearance of a Thin Layer Asphalt Concrete (AC-BBM).......... 95 Figure 27: Cross-section of an SMA (Stone Mastic Asphalt) .................................... 98 Figure 28: Surface appearance of an SMA (Stone Mastic Asphalt).......................... 98 Figure 29: Nomograph for calculating mix stiffness modulus values ...................... 119 Figure 30: Example of GC variability in the percentage of voids obtained onsite ... 129 Figure 31: LCPC Fatigue Carousel......................................................................... 132 Figure 32: Results obtained with the Large Device wheel tracking Tester -

Study of laboratory rutting...................................................................... 133 Figure 33: Results obtained with the Large Device wheel tracking Tester -

Study of rutting on plant-produced mixes .............................................. 133 Figure 34: Behavior of mixes on the LCPC test carousel, evolution of rut depth

submitted to a single large wheel (F = 42,5 kN, V = 40 km/h) ............... 134 Figure 35: In situ core sampling.............................................................................. 136 Figure 36: In situ sawing......................................................................................... 136 Figure 37: Variability in stiffness modulus on in situ extractions (site no, 1) ........... 137 Figure 38: Variability in stiffness modulus on in situ extractions (site no, 2) ........... 137 Figure 39: Laboratory-worksite correlation: Stiffness modulus at 15°C

(0,02 sec or 10 Hz) ................................................................................ 139 Figure 40: Summary of fatigue test results by sample preparation

protocol (preliminary design, laboratory verification, onsite extractions) ............................................................................................ 140

–12 –

Table 1 – Typical filler characteristics for asphalt mixtures....................................... 43 Table 2 – Specification on fines from fine aggregate or all-in aggregate or

(in their absence) from mixed fillers ........................................................ 43 Table 3 – Indicative minimum characteristics of coarse aggregates : Mechanical

strength and production characteristics .................................................. 46 Table 4 – Accepted values of D vs. type of mixture.................................................. 47 Table 5 – Reclaimed asphalt characteristics vs. reuse rate...................................... 51 Table 6 – Overall limits of target composition ........................................................... 52 Table 7 – Minimum Binder content and richness modulus values ............................ 53 Table 8 – Test specimen characteristics .................................................................. 56 Table 9 – Specifications relative to the void percentage........................................... 58 Table 10 – Specifications relative to water resistance .............................................. 59 Table 11 – Specifications relative to the wheel tracking test..................................... 60 Table 12 – Specifications relative to the stiffness modulus....................................... 61 Table 13 – Specifications relative to fatigue resistance ............................................ 61 Table 14 – TYPE TESTING Required material quantities – Approximate testing

durations................................................................................................. 63 Table 15 – Types of tests for asphalt mixes ............................................................. 64 Table 16 – Type of tests for BBTM (very thin layer asphalt concretes) .................... 66 Table 17 – Type of tests for soft asphalt concretes .................................................. 67 Table 18 – Type of tests for Hot Rolled Asphalt ....................................................... 68 Table 19 – Type of tests for the Stone Mastic Asphalt material................................ 69 Table 20 – Type of tests for the porous asphalt........................................................ 70 Table 21– Suggested bitumen grade by mix type..................................................... 80 Table 22 – Initial AC20 or AC14 Grave-Bitume A C-GB and High Modulus

Asphalt Concrete AC-EME grading curve............................................. 87 Table 23 – Initial AC10-EME grading curve.............................................................. 87 Table 24 – Typical initial binder content of AC-GB and AC-EME

(richness modulus) ................................................................................. 88 Table 25 – Initial AC-BBSG, AC-BBS and AC-BBME grading curve ........................ 91 Table 26 – Initial BBSG, BBME and BBS richness modulus and binder content...... 92 Table 27 – Initial PA-BBDr grading curve ................................................................. 93 Table 28 – Initial Porous Asphalt (PA-BBDr) binder content (Richness modulus) .... 95 Table 29 – Initial AC-BBM and BBTM grading curve................................................ 97 Table 30 – Initial AC-BBM, BBTM and mixes for UTLAC (BBUM) binder content .... 98 Table 31 – Initial SMA grading curve........................................................................ 99 Table 32 – Initial SMA binder content ....................................................................... 99 Table 33 - Composition effect on Gyratory Compactor test results ........................ 109 Table 34 - Composition adjustment in order to correct Gyratory Compactor

results ................................................................................................... 110 Table 35- Effects of mix design factors on % rutting............................................... 113 Table 36 - Practitioners' advice - Enhancing rutting resistance .............................. 113 Table 37 - Typical © values (in MPa)...................................................................... 115 Table 38 - Practitioners' advice - Duriez test results adjustment ............................ 115 Table 39 - Fatigue - loss of linearity relationship .................................................... 121

–13 –

Table 40 - Adjustment to average texture depth..................................................... 123 Table 41 - Practitioners' advice – Mix refinement [for a given type of mix] –

Summary of the effect of mix design factors......................................... 124 Table 42 - Site conditions ....................................................................................... 128 Table 43 - % of void measurements – Comparison of laboratory compactor results

(design, verification) with onsite results (Gyratory compactor, bulk density (MVA) measurement using gamma-densitometry) ............................... 130

Table 44 – Comparison between the field behavior of material mixes and the acceptance or rejection criterion according to French specifications .... 135

Table 45 – Test repeatability and reproducibility values ......................................... 160

LPC Asphalt Mix Design Guide - Résumé/Abstract -

–14 –

Résumé

Manuel LPC d’aide à la formulation des enrobés

Jean-Luc DELORME

Chantal de La ROCHE

Louisette WENDLING

Le manuel LPC d’aide à la formulation des enrobés est destiné aux laboratoires qui mettent au point des mélanges hydrocarbonés. La méthode de formulation fait appel aux caractéristiques des constituants, à la tenue à l’eau, au pourcentage de vides à la Presse à Cisaillement Giratoire, à la résistance à l’orniérage, au module de rigidité et à la résistance en fatigue. Les exigences normatives nécessaires à la réalisation d’une épreuve de formulation sont synthétisées dans la deuxième partie. Elles tiennent compte de l’expérience française et de l’application des normes européennes. La partie consacrée à la mise au point des mélanges est fondée sur l’expérience du réseau LPC, exprimée à partir des résultats d’un groupe de travail, elle comporte des recommandations pour optimiser les caractéristiques du matériau. Ces recommandations s’appuient sur des cas concrets, sur des plans d’expérience spécifiques ou font appel à des références bibliographiques. Les relations entre les caractéristiques de laboratoire et celles obtenues sur chantier proviennent de travaux de recherche LPC réalisés sur les matériaux structurants. Ils permettent de faire la relation entre une population de résultats de laboratoire et une population de résultats de chantier sur les pourcentages de vides à la Presse à Cisaillement Giratoire, l’orniérage, le module et la résistance en fatigue des enrobés.

LPC Bituminous Mixtures Design Guide - - Résumé/Abstract -

–15 –

Abstract

LPC Bituminous Mixtures Design Guide

Jean-Luc DELORME

Chantal de La ROCHE

Louisette WENDLING

This LPC Mix Design Guide is intended for road research laboratories assigned to design bituminous materials mixes The mix design methodology is based on component characteristics, water-sensitivity testing, void content assessments using gyratory compaction, resistance to permanent deformation, stiffness and fatigue resistance. Normative requirements by type of test will be summarized in the second part taking into account the French experience and the European standardization. The part of this report devoted to the actual mix design is based on the experience of a working group from the LPC network and includes recommendations for optimizing material characteristics. Such recommendations are based on practical cases, specific experiments or bibliographical research. Relationships between laboratory characteristics and jobsite characteristics have been established from LPC studies on structural materials; they serve to correlate a dataset of results obtained in the laboratory with another set obtained on the jobsite, with respect to void content, by means of gyratory compaction, rutting resistance, stiffness and fatigue resistance.

LPC Bituminous Mixtures Design Guide – General remarks –

- 17 -

1 GENERAL REMARKS – BASES OF THE METHOD

1.1 Introduction

1.1.1 The various mix design approaches

Design methods for bituminous mixes have been developed over the past forty years in order to satisfy the latest requirements issued by road builders and engineering companies. Rising traffic loads, along with the integration of safety, comfort, durability, maintenance and user nuisance considerations, under given climatic conditions and within a defined technical context (design and dimensioning of pavements layers), has incited increasingly-complex material design approaches. Asphalt mix design becomes even more sophisticated in improving one characteristic, while changing the composition exerts a negative influence on another characteristic. One well-known example is that an increase in binder content has a beneficial impact on fatigue resistance, yet diminishes rutting resistance. The properties sought for a given bituminous material depend on the intended layer of application. For bases and base-courses, whose role is to distribute loads over the supporting soil without incurring excessive deformation, the overlay course must basically be stiff, fatigue-resistant, resistant to permanent deformations and relatively compact. For a wearing course in direct contact with traffic and aggressive climatic agents, emphasis is placed on: durability with a high resistance to water action, resistance to permanent deformations, and especially on the search for satisfactory surface characteristics (roughness, rolling noise, photometry, etc.). Furthermore, depending on the specific design case, the wearing course must be compact enough to protect the lower layers from water infiltration, yet open enough to enable water to drain. The characteristics sought are multifaceted and sometimes contradictory. This topic has been addressed in a variety of ways and depends heavily on the local context. A state-of-the-art assessment of asphalt mix design procedures across various countries was produced within the scope of a RILEM technical committee work program [Rilem Report 17, 1998] and distinguished six design methods:

1. "recipe ", 2. empirical testing, 3. analytical computations, 4. volumetric method, 5. performance related testing, and 6. fundamental testing.


- 18 -

The (cookbook) recipe method relies upon local experience a known composition, which has already yielded satisfactory results under a given set of use conditions over long periods of time, is reproduced. The application of such cookbook recipes could, on occasion, be supplemented by a handful of tests stemming from empirical methods. The most widespread method employing empirical tests is known as Marshall's method [ASTM DI-559-60T]. Specimens are compacted according to established operating procedures, and mechanical test results are compared with observed on-site behavior. The analytical method is based on component properties and a mix model for both calculating the percentage of voids and estimating material performance. This method has been developed primarily in Belgium. The volumetric method consists of deducing the respective proportions, expressed in volume terms of the granular skeleton, the bitumen and the available volume (percentage of voids) of a compacted specimen under previously-established conditions; this allows determining mix behavior without conducting any additional mechanical tests. The performance related method that calls for conducting tests on the basis of material properties makes use of simulation techniques, directly correlated with the target property; such is the case with the rutting test, run like a traffic simulation. The so-called "fundamental" method comprises tests whose results may be directly used as input data into material design models. This would specifically pertain to dynamic modulus or fatigue resistance values.

European standardization of hot bituminous mixtures has served to formalize and summarize the principles behind this classification, by means of distinguishing between two approaches: "empirical" and "fundamental". The empirical approach contains the "recipe" or "prescriptive" phase (to a rather considerable extent), the "volumetric" phase, the "empirical testing" phase and, where applicable, "performance related" tests. The fundamental approach encompasses a scaled-back "prescriptive" ("prescription") phase, a "volumetric" phase, "performance related" tests and "fundamental" tests. The two approaches cannot neglect a descriptive section devoted to constituent characteristics, especially aggregates, given that the properties targeted by the fundamental tests are not always sufficient to satisfy the desired set of requirements. Mix design work is performed on materials either recomposed in the laboratory or extracted directly following fabrication at the plant. Two phases can in fact be distinguished under the heading of material mix design: type testing, and refinement or optimization of the mix design formula. Type testing is typically performed according to a formalized protocol since it often serves as the basis for contractual relations, whereas the formula optimization phase (mix design) relies upon the experience of the mixtures designer.


- 19 -

European standardization clearly distinguishes type testing, which lies within the regulatory domain to substantiate "EC" branding policy, from non-codified formula optimization (mix design). Some design methods contain both the testing part and the optimization part. Such is the case for example with both the Marshall method, which actually predicts a possible optimization (based on the percentage of voids, stability and creep), and the "Superpave" method (optimization of the percentage of voids and binder content, as a function of expected traffic).

1.1.2 Type testing procedures applied in France

The type testing procedure applied on French roads is defined by appropriate standards; it has been characterized by an approach based to the greatest extent possible on asphalt mix performance. For structural type materials, it may be classified within the "fundamental" approach. For other material types, the approach is qualified as empirical, as intended in the European standardization, even though it involves “performancerelated" testing. The recipe method is not used herein. In contrast, volumetric considerations have been taken into account by means of the gyratory compactor: this test serves as the focal point of the method since it is used for all types of hot bituminous mixtures (with the exception of mastic asphalts mixes, which remain beyond this document's scope of application). Type testing is conducted with materials prepared in the laboratory representative of the planned jobsite and that expose performance thresholds. Type testing imposes specifications on the components, and especially on the aggregates. It relies upon tests on the gyratory shear press, water resistance, rutting resistance, stiffness modulus and fatigue resistance. The mix design method is entirely dissociated from type testing and has not been codified. The approach based on this principle has been practiced for the past thirty years; it was first formalized in a series of SETRA-LCPC technical documents and then in the French standards. The current European standards, which are replacing the French standards, do not challenge this principle.

1.2 Presentation of this document

This asphalt mix design guide has been drawn up from the conclusions forwarded by the working group introduced in the preface. This effort was complemented, in particular for Part 4, by results from research conducted within the framework of specific LCPC programs (Research topic CH15: Design of the hot bituminous mixtures). In this introductory part, the operating principle behind the tests selected will be briefly recalled, along with the set of definitions and relationships necessary for conducting type testing or bituminous mixtures design. Other definitions have been included in the glossary, see Appendix F.


- 20 -

Part 2 is devoted to type testing, which is fully defined within the standard reference. Test standards associated with applicable reference systems have been listed in Appendix A, and the list of current standards in effect is provided for asphalt mix components (aggregates, bitumen), preparatory tests, the actual tests, methodological references stemming from either the specific standards derived or general standards. Depending on the level of requirements, the sample contains a varying number of tests with thresholds ranging in severity depending on material use and type. Yet these test results are always accompanied by requirements issued on the components, particularly the aggregates. Part 2 offers a summary of the existing inventoried requirements, at times shared among different documents. European standards are taken into consideration in this part. The list of European standards with their French correspondence will constitute Appendix B, along with pertinent application recommendations and comments. When European standards give rise to modifications, all relevant chapters will be highlighted. The objective of Part 3 is to lay out the formula optimization and adjustment methods in practice throughout France's Ponts et Chaussées (LPC) research network. Indications will be given regarding the choice of constituents and test result interpretations, especially those from the gyratory shear press, in order to derive a mix that fulfills all target characteristics. Recommendations will be provided for adjusting the asphalt mix composition whenever test results on a given study mix are not satisfactory. This part has been written using the results from specific experimental campaigns or as a means of transmitting the practices set forth either by experts working with the laboratory network or in bibliographical references. Part 4 focuses on pertinent laboratory-worksite correlations. Since the type testing specified in works contracts is conducted entirely in the laboratory, it proves essential to ensure that the "industrial" production of road overlays on site enables obtaining equivalent characteristics at the worksite. This chapter will discuss the results generated within the scope of research project CH15: "Design of hot bituminous mixtures", for the percentage of voids with the gyratory compactor, stiffness modulus and fatigue resistance values.

1.3 Test protocols in application

The primary tests used for type testing will be outlined below. The French and European reference standards are listed in Appendices A and B, respectively. These tests have given rise to precision experiments in order to determine their repeatability r and reproducibility R. Repeatability r and reproducibility R measures have been summarized in Appendix D.


- 21 -

1.3.1 Gyratory compactor

Operating principle: The hydrocarbon mix, prepared in the laboratory, is set, bulked and brought to the test temperature (approx. 130° to 160°C) within a cylindrical mold 150 or 160 mm in diameter. A 0,6-MPa vertical pressure is then applied on the top of the specimen. At the same time, the specimen is slanted slightly at an angle on the order of 1° (external) or 0,82° (internal) and submitted to circular movement. These various actions exert a compaction by means of kneading. The increase in compactness (i.e. via the decrease in percentage of voids) vs. the number of revolutions can then be observed. Interpretation: For a given number of gyrations, to be determined depending on the type of mix, the nature of aggregates and the application thickness, the materials designer is able to predict the percentage of voids on site. In the case of very thin wearing courses, this test focuses more on estimating the macro-texture than the compacity.

Figure 1: Gyratory Compactor – MLPC Type 2

Figure 2: Gyratory Compactor – MLPC Type 3

The test is highly sensitive to mix design factors, such as "friction" of the granular skeleton (angularity) and binder content. This test also serves to detect and assess the risk of rutting.


- 22 -

Thanks to the speed offered by this means of testing, the gyratory compactor proves a highly-valuable instrument for the materials designer. Moreover, it enables detecting the type of changes that go unnoticed during more common tests conducted on aggregates. The gyratory shear press makes it possible to verify formula consistency over time. Specifications are applicable to all types of bituminous mixtures; they stipulate a range of void percentages to be respected for a given number of gyrations.

1.3.2 Water resistance sensitivity

Water resistance is at the bases of the bituminous mixtures durability. It used to be measured by means of the Duriez test, within the scope of French standardization practices. However, the European standardization includes two different procedures indirect tensile test and direct compression test derived from Duriez test. Those two procedures give equivalent results, however the repeatability reproducibility of the direct compression test (Duriez test) are about twice better the ones of the indirect tensile test.

1.3.2.1 Direct compression test (Duriez test)

Operating principle: The hydrocarbon mix is compacted in a cylindrical mold undergoing double-effect static pressure. A group of specimens is conserved without any controlled temperature immersion (18°C) or relative humidity immersion, while the other group is held immersed. Each specimen group is then loaded under simple compression. Results interpretation: The ratio of resistance following immersion to dry resistance yields the water resistance value for the mix. Dry resistance represents one approach to describing mechanical characteristics, while compacity constitutes a complementary indicator to the gyratory test.

1.3.2.2 Indirect tensile test

Operating principle: Cylindrical specimens are either produced with the gyratory compactor or cored from plates. A group of the specimens is conserved without immersion at room temperature, while the other portion is held immersed after extensive degassing during 70 hours at 40°C. Each specimen group is then loaded under diametric compression at 15°C. Test interpretation: The ratio of the resistance post-immersion to the dry resistance yields the mix's water resistance.


- 23 -

1.3.3 The wheel tracking test (large device)

Operating principle: The test specimen here is a parallelepiped plate 5 cm or 10 cm thick, depending on whether the application thickness of the mix happens to be less than or greater than 5 cm. This plate is submitted to a one-wheel traffic load (frequency: 1 Hz, load: 5 kN, pressure: 0,6 MPa) under severe temperature conditions (60°C). Test interpretation: The depth of deformation produced when the wheel crosses over the bituminous mixture is measured vs. the number of cycles. Test specifications pertain to a rut percentage at a given number of cycles, which in turn depends on the type of material and its classification.

Figure 3: Large-device wheel tracking test Figure 4: Detail of the rut depth measurement

1.3.4 Stiffness testing

Operating principle: Asphalt mix stiffness is determined by either a complex modulus test (sinusoidal loading on a trapezoidal or parallelepiped specimen) or a uniaxial tensile test (on a cylindrical or parallelepiped specimen). The load is applied over a domain of small deformations, through controlling time or frequency, temperature, and the loading law. Test interpretation: The modulus (stress-strain ratio) is computed for each basic test. Using the time-temperature equivalence, the modulus master curve is plotted at a given temperature. This depiction provides information on bituminous mixture behavior over a broad load or frequency time spectrum.


- 24 -

The test specification pertains to the modulus at 15°C and a frequency of 10 Hz or a loading time of 0,02 sec.

Figure 5: Complex modulus testing machine -MLPC 3MC

Figure 6: Adjustment of the displacement sensor

Figure 7: Rheologically-controlled testing machine

Figure 8: Specimen set-up


- 25 -

Fatigue resistance

Operating principle: A trapezoidal specimen is submitted, at a set temperature and loading frequency, to an imposed deformation. When the stress applied to maintain a constant deformation is halved, the specimen is considered damaged at the corresponding number of loading cycles. Test interpretation: On a lg/lg graph, the various couples (loading level, number of cycles until reaching damage) may be presented on a fatigue line. Once 10

6 cycles have been completed, the loading threshold read on the line is the

Figure 9: Fatigue test in 2-point bending on trapezoidal specimens

1.4 General remarks on bituminous mix components Bituminous mixes are composed of a mix of aggregate particles whose size varies between 0 and D (mm) and a hydrocarbon binder. Additives may be included in this mix in order to improve performance. The final mix, once compacted and cooled, features a nonzero void content, which serves to enhance product performance.


- 26 -

1.4.1 Aggregates

Figure 10: View of quarry face Figure 11: Screening-crushing

1.4.1.1 Fillers The fines content (i.e. passing the sieve 63 µm) of a bituminous mixture is generally a combination of added filler in small proportion and a majority of fines coming from fine aggregates (or all in aggregates 0/4). The added filler may stem from solid rocks: limestone filler is used extensively. Other materials also get employed, such as cement, quicklime, activated filler (mix of limestone fines and hydrated lime), hydrated lime, fly ash, cement fillers and slates.

1.4.1.2 Fine aggregates 0/2 and all in aggregates 0/4 Crushed 0/2 fine aggregates with a fine content of 18% and crushed 0/4 all in aggregates with a fine content of 10% to 14 % are mostly often used for the road construction. The particle size distribution (grading) of a mix with fine aggregates (and/or all in aggregates 0/4) and coarse aggregates from different origins might therefore display anomalies (discontinuities or lumps). Fine aggregates with totally round particles are also used in order to improve mix workability.

1.4.1.3 Coarse aggregate Coarse aggregate (d/D) constitute the "backbone" of the hydrocarbon mix. As such, their composition, angularity and shape all serve to influence, at least in part, both mix stability and the surface characteristics of surface courses. Moreover, their mineralogical nature exerts a direct impact on the mix design: some materials (basalt, granite, gneiss) are more difficult to compact, while others exhibit an absorbent characteristic (basalt, slag, dolomitic limestone), which must be taken into account


- 27 -

when deriving binder concentration. The mineralogical nature and state of cleanliness also influence bitumen-aggregate adhesion.

1.4.1.4 Particle size distribution curves The ultimate granular material is obtained by mixing various granular fractions (d/D) entering into the composition. Each fraction is characterized by a particle size distribution that indicates the passing percentages through the range of standardized sieves6. The particle distribution curve or grading curve is characteristic of the final material.

1.4.2 Binder

The binder may be either a pure, modified or special bitumen (hard, pigmentable, colored bitumen, or regeneration binders), or a synthetic binder. In the absence of other data, bitumen mass density is set equal to 1,03 Mg/m3.

1.4.2.1 Pure bitumen

This category comprises the range of standardized paving grade bitumen according EN 12591 and those special bitumens distinguished by “hard” grade according EN 13924, and low thermal susceptibility bitumens.

1.4.2.2 Modified bitumen

Modified bitumen materials consist of bituminous binders whose properties have been modified through the use of a chemical agent, which when introduced into the basic bitumen modifies the chemical structure and physical and mechanical properties. This category of material has been codified in EN 14023, which remains more of a description than any actual performance-based classification. These bitumens are prepared prior to application within a specialized unit. The chemical agents employed include natural rubber, synthetic polymers, sulfur and other organic-metallic compounds. The primary chemical agents used to modify bitumens are :

• The Thermoplastic elastomeric polymers SBS (Styrene Butadiene Styrene) SIS (Styrene Isoprene Styrene) SB (Styrene Butadiene) SBR (Statistical copolymer)

• Thermoplastic plastomeric polymers EVA (Ethylene vinyl acetate) EMA (Ethylene methyl acrylate) EBA (Ethylene butyl acrylate) PIB (Polyisobutylene)

• Latex 6 The base series of the sieve is composed of the following elements (in mm): 0,063; 0,125; 0,250; 0,500; 1; 2; 4; 8;16; 31,5.


- 28 -

Polychloroprene SBR rubber Natural rubber Crumb rubber

Elastomer-modified binders: Physical mixes are to be distinguished from elastomeric bitumens obtained by means of cross-linking. Physical mixes are typically heterogeneous to a scale of several micrometers. The fineness of the elastomeric bitumen structure will exert a direct influence both on the stability of the asphalt mixture and on its physical properties over the entire temperature range. Cross-linked elastomeric bitumens exhibit a structure resulting from a dual form of extremely fine links, on the order of one micrometer. This reaction is irreversible. Cross-linked elastomeric bitumen displays higher tensile strength and stiffness and increased ductility in comparison with the initial binder. Elastomeric bitumen modification induces differences in rheological behavior. In comparison with pure bitumen, BmP SBS at low temperature exhibits lower modulus values, hence greater flexibility; this situation becomes reversed at high temperatures. For a given bitumen sample, this modification in rheological behavior depends on both polymer nature and content.

Plastomer-modified binders: Ethylene copolymer bitumen (EVA, EMA and EBA): At low polymer content (< 5%), the modification in material properties is due primarily to the increase in asphaltene concentration within the bitumen phase. In this case, the choice of the base bitumen is predominant. At high polymer levels, the polymer component is plasticized by a fraction of the maltenes found in the bitumen and the choice of polymer influences binder properties. A decrease in penetrability coupled with a strong increase in ring and ball temperature can be observed. Ethylene – polybutylene (PIB) copolymeric bitumens: The addition of PIB in road bitumen materials serves to lower the vulnerability to cold weather. The joint use of PIB and EVA enables improving simultaneously the behavior at both high and low temperature. With the exception of PIB-EVA binders, copolymeric bitumen mixes are rarely stable when stored (except for content levels < 3% EVA and binders with low asphaltene concentrations). It thus becomes necessary to stir or remix the binder.

Rubber bitumen: Non-storable rubber bitumen: Produced using a crumb rubber obtained by means of grating both natural and synthetic rubber, rubber bitumen displays an elastomeric characteristic, along with


- 29 -

significant viscosity at high temperature and considerable flexibility at low temperature. Storable rubber bitumen: Produced using ground worn tires from trucks and cars, heavy oil and a synthetic elastomer, rubber bitumen displays extreme elongation upon failure at low temperature.

1.4.2.3 Pigmentable bitumen

This category of bitumens is obtained from untreated material samples and characterized by a very low asphaltene content. The grades are the same as with conventional road bitumens. The material is colored by means of metallic oxides at an approximate mass concentration of 2,5% to 6% of the total mixture.

1.4.2.4 Synthetic binders These binders are obtained by mixing petroleum and petrochemical fractions without asphaltenes. They appear as a thin transparent film, which makes it possible to retain the natural hue of the aggregate; moreover, they can be colored by adding 2% pigments.

1.4.2.5 Bituminous binders with mineral loads

These ready-to-use binders are obtained as a plant mix using pure bitumen and mineral loads, e.g. lime. Binder content differs from bitumen content.

1.4.2.6 Agrochemical binders

These binders are made from vegetal matter without any petrochemical byproduct. The result is transparent and may be colored. Its applicability is currently undergoing evaluation.

1.4.2.7 Kerosene-proof bitumen These bitumens have been specially designed to withstand the risk of dissolution due to kerosene losses on parking surfaces and on airport strips/runways. They may be applied in the composition of airport asphalt concretes.

1.4.2.8 Rule for bitumen mixes It may prove useful to conduct certain tests on the basis of recomposed bitumens with known penetrability or ring and ball temperatures (e.g. for a rutting test using a bitumen with a preset ring and ball temperature value).


- 30 -

Penetrability: 100 x log P = a log P1 + b log P2 where a and b are the respective proportions of 2 bitumens with penetrability values of P1 and P2. Ring and ball temperature: 100 T = a T1 + b T2 a and b are the respective proportions of 2 bitumens with ring and ball temperatures T1 and T2 (in °C).

Figure 11: Penetrability test Figure 12: Ring and ball temperature test

1.4.3 Additives Additives are intended to improve asphalt mix properties. They may be introduced either into the formula at the time of mixing or directly into the bitumen tank.

1.4.3.1 Adhesion enhancers In order to improve the reciprocal affinity between binder and aggregates while ensuring durability, adhesion enhancers may be employed. This category of additive pertains essentially to tensioactive nitrogen compounds derived from fatty acids (e.g. amines, polyamines…) with a bitumen concentration of approximately 0,3% to 0,6%. The lime or limestone fines, with concentrations reaching 1% bitumen, can also be used as such adhesion enhancing agents.

1.4.3.2 Polyethylene

Origin: cable waste material, crushed milk bottles, polyethylene films, new polyethylene.


- 31 -

Polyethylene wastes often consist of a mix of high-density and low-density polyethylene. During melting at temperatures of around 130°C, polyethylene gets partially combined with bitumen. The concentration tends to lie between 0,4% and 1% of the aggregate quantity. The proportion of polyethylene with respect to bitumen can thus vary from 20% to 66%.

1.4.3.3 Polymers

Polymers assume the form of pellets incorporated during the mixing stage.

1.4.3.4 Crumb rubber and 2/6 rubber aggregates

Incorporated into the formula upon mixing, the rubber is partially combined with bitumen. The manufacturing temperature is greater than that of pure bitumen, with the mass density of rubber being 1,15 g/cm3.

1.4.3.5 New fibers and recycling Fibers can be mixed in with the binder either as a preliminary step, or introduced into the dry mix, or following incorporation of the bitumen. Depending on the type of fiber, the laboratory preparation procedure must be adapted while respecting the mode of industrial addition. Various types of fibers are used with this configuration:

Glass These are inorganic fibers with a length of between 100 µm and 10 mm, and a diameter on the order of 5 µm to 6 µm. The choice of surface treatment influences the induced properties. Typical concentrations amount to around 0,8% with respect to aggregate quantity. Their mass density equals 2,5 g/cm3 and their theoretical specific surface area is 0,3 m2/g.

Cellulose This is a natural fiber with a length of between 900 µm and 1,1 mm, and a diameter on the order of 15 - 50 µm. It may be pre-mixed in the form of pellets with a maximum concentration of 0,3% of aggregate quantity. Mass density equals 0,9 g/cm3 and the theoretical specific surface area reaches 0,16 m2/g.

Rock fibers This category of mineral fibers features a length lying between 200 µm and 2 mm, and a diameter in the range of 3 to 5 µm. Mass density stands at 2,7 g/cm3 and the theoretical specific surface area at 0,6 m2/g.

Polyester These fibers are synthetics with a length of between 600 µm and 1,2 mm, and in some instances may even reach 6 mm. They can withstand temperatures of up to 220°C, with a concentration on the order of 0,6% of the aggregate quantity.

Composite These fibers stem from recycled products, e.g. automobile parts.


- 32 -

1.4.3.6 Natural bitumens and asphalts

Purified Trinidad bitumen: Purified bitumen is extracted by means of refining; it contains a mineral portion and features a mass density in the neighborhood of 1,40 g/cm3, a penetration at 25°C between 1 1/10 mm and 4 1/10 mm, and a ring and ball temperature greater than 90°C. (The "soluble" bitumen exhibits a standard penetration of 3 to 12 1/10 mm and a ring and ball temperature of between 68° and 78°C).

Figure 14: Example of extraction on Trinidad Lake (Venezuela)

50/50 Trinidad powder This asphalt mix is composed of 50% purified Trinidad bitumen and 50% limestone filler.

Gilsonite® Gilsonite is a natural hydrocarbon that assumes a 0/2 form, with a mass density of 1,05 g/cm3, a standard penetration of around 0 (1/10 mm) and a ring and ball temperature greater than 150°C. The concentration extends from a few percent to 10% of the dry aggregates.


- 33 -

1.4.3.7 Pigments The pigments used in road mix techniques are mineral pigments that prove stable when exposed to mixing temperatures and light. The most widespread would be the following metallic oxides:

- red, yellow or gray iron oxides, - light yellow lead chromate, - green chrome oxide, - blue cobalt oxide, - white titanium oxide.

Figure 15 : Examples of colored asphalt mixes

1.5 Useful definitions and relations for type testing

Most definitions are listed in the glossary found in Appendix F. Only those notions essential to type testing have been discussed below, along with the useful relationships between parameters. When necessary, the European names corresponding with the magnitudes derived below will be indicated for each definition provided in Appendix F.


- 34 -

1.5.1 Binder content

For the former French standards contained in the series NF P 98-130 to 98-141, binder content is TLext, which represents the ratio of the binder mass to the dry aggregate mass, expressed as an external percentage. For this reason, the binders contents of the examples given in the present guide are usually expressed in terms of TLext.

massaggregateDry

massBitumenTLext ×= 100

The EN "product" standards included in the series EN 13108 impose the value tlint, which is the ratio of binder mass to the total mix mass, expressed as an internal percentage.

massbitumensmasaggregateDry

massBitumentl+

×= 100int

tlint and TLext are correlated by the following equations:

int

int

100100

tltl

TLext −

×=

ext

ext

TLTLtl

+×

=100100

int

Appendix C contains a table of equivalences between binder contents.

1.5.2 Richness modulus K

The richness modulus K [Duriez, 1950] is a value proportional to the conventional thickness of the hydrocarbon binder film coating the aggregate. K is independent of the density of the granular mix; it is correlated with external binder content via the following equation:

5 Σ×= αKTLext

where Σ is the specific surface area, expressed in square meters per kilogram, determined by the relation:

100 Σ = 0,25 G + 2,3 S + 12 s + 150 f with: G the proportion of aggregate particles greater than 6,.3 mm S the proportion of aggregate particles included between 6,3 mm and

0,250 mm s the proportion of aggregate particles between 0,250 mm and

0.,063 mm f the proportion of aggregate particles less than 0,063 mm

α a correction coefficient relative to the density of aggregates


- 35 -

α = 2,65 / ρG, with ρG being the mass density of aggregates in grams per cubic centimetre.

It is still possible to use the richness modulus, while using tlint, the equations being then:

( )5

5

100100

Σ×+Σ××

=αα

KKtlint

and

5

100100

Σ

⎟⎟⎠

⎞⎜⎜⎝

⎛−×

=α

int

int

tltl

K

NOTE: This calculation is not applicable whenever the mix contains special fines or additives, such as fibres.

1.5.3 Percentage of voids or compacity

1.5.3.1 Definitions

Percentage of voids The percentage of voids, or compacity, of bituminous mixtures constitutes a very important parameter in the field of bituminous mixtures design. Material properties depend in fact on the respective volumes of the granular skeleton, the binder (ultimately including additive volumes as well) and "free" air, called percentage of voids or void content The percentage of voids under conditions of imposed compaction – in general using the gyratory compactor – is the leading requirement during mix preparation. This requirement matches the characteristics sought on site: texture, durability (water resistance, fatigue resistance, rutting resistance), etc. For this reason, specimen preparation is closely associated with percentage of voids requirements. In order to verify in situ that the expected characteristics actually correspond well with the properties observed in the laboratory, measurement of the percentage of voids proves to be one of the key points for verification.

Volumetric composition The volumetric composition of a mix has been represented on the diagram in Figure 1, in conjunction with the following notations: Apparent volume VT: This amount is the total specimen volume. It is dependent upon the chosen measurement method, especially the inclusion of specimen surface irregularities. Void volume Vm: This value represents the volume of the asphalt mix's pores and interstices. Solid volume Vr: This amount encompasses the volume of aggregate, bitumen and additives with the exception of voids, pores and interstices. It is generally expressed in percentage terms with respect to the apparent volume.


- 36 -

Voids in Mineral Aggregates - VMA This quantifies the space available within the granular mix and represents the sum of volumes occupied by the free bitumen and the air voids. It is also expressed as a percentage with respect to apparent volume. Bitumen volume Vb: This corresponds to the total bitumen volume within the mixture. Bitumen volume absorbed by aggregates (vba): This volume of bitumen penetrates into the aggregate pores. The absorption process depends on aggregate porosity; it may be evaluated from the deviation between the mix's actual computed mass density and actual measured mass density (see Section 1.5.3.2). Volume of free bitumen vbl This is the bitumen volume that does not penetrate into aggregate pores. Vb = vba + vbl

Voids filled with bitumen VFB This parameter, measured as a percentage, is the ratio of binder volume to void volume of the granular skeleton and gets incorporated into certain design methods in order to ensure a sufficient volume of mastic (binder + filler) within the mineral skeleton.

Figure 16: Volumetric approach to developing an asphalt mix

Void volume Vm

Bitumen volume absorbedby aggregates vba

Bitumen volume Vb

Aggregates volume Vg Apparent volume VT

volume of free bitumenvbl

Solid volume Vr

Voids in mineral aggregates VMA


- 37 -

The distribution of voids within the mix, figure 17, allows to distinguish interconnecting voids whose geometry enables associating two faces of a pavement or of a sample . This type of void is sought in the case of porous asphalts. The geometric complexity of such voids, with respect to the possibility of internal fluid flow, is called "tortuousity". Non-connecting voids open onto one face yet are blocked at the other end. During measurement of the bulk density, depending on the method employed, they may be taken into account or not, or perhaps only in part, within the volume selected for the computation. Occluded voids are not accessible.

Figure 17: Connecting, non-connecting and occluded voids

Maximum density The maximum density may be directly determined on the mix according to Standard EN 12697-5 using Method A with water, in which case it gets denoted MVR. It may be calculated from component mass densities obtained by means of various methods (water, solvent, paraffin oil) and would then be denoted MVRc, based on the following formulas:

VbVgmassBitumenmassAggregateMVRc

++

=

Case of an external binder content TLext:

b

ext

gn

n

gg

ext

TLG%....G%G%TL

MVRc

ρρρρ++++

+=

2

2

1

1

100

Case of an internal binder content tlint:

b

int

gn

n

gg

tlG%....G%G%MVRc

ρρρρ++++

=

2

2

1

1

100

Non connecting voids

Occluded voids

Connecting Voids


- 38 -

where %Gi are the mass percentages of granular fractions and ρgi their respective mass densities. It should be pointed out that in the formula corresponding to the case TLext, %G1+%G2 +…+ %Gn = 100, whereas in the formula corresponding to the case tlint, %G1+%G2 +…+ %Gn = 100 - tlint.

ρb is the mass density of bitumen. The MVRc value depends on the method chosen for measuring the mass density of components and in particular that of aggregates. If aggregate mass densities are measured by methods using fluids, whose viscosity enables penetrating into grain porosities (water, solvent), the MVRc value may be overestimated. This method is also employed to determine the quantity of bitumen absorbed. When aggregate mass densities are determined using a paraffin oil whose viscosity lies near that of the bitumen, the calculation method and direct measurement yield similar results.

Bulk density Bulk density is derived from the ratio of the sample mass to its apparent volume. This apparent volume may be determined by means of geometric measurement (MVA) or hydrostatic weighing, with or without paraffin EN 12697-6) depending on the material voids content (MVa). The bulk density can also be assessed using a Gamma bench measurement: MVaγ (EN 12697-7).

Percentage of voids and compacity The compacity and percentage of voids are derived from both actual mass density measurements MVR and bulk density measurements MVA (MVa or MVaγ), using the following relations:

C% = 100 x (MVa or MVA or MVaγ) / MVR

v% = 100 [1 - (MVa or MVA or MVaγ) / MVR]

1.5.3.2 Relations between parameters

Voids content and compacity Compacity C% and the percentage of voids v% are correlated by the following equation: 100 = C% + v%


- 39 -

Volume of voids in mineral aggregate VMA


VMA% (or air voids and free bitumen) = ⎟⎟⎠

⎞⎜⎜⎝

⎛+

−××−

)TL())v(MVR(

extg 100100100100

ρ

gTL

TLMVR)v(g%VMA ext

ext

ρ

ρ ⎟⎟⎠

⎞⎜⎜⎝

⎛−

−×⎟⎠⎞

⎜⎝⎛ ×−

−

=100

1100

100


MVAtlvVMAb

×+=ρ

int%

Volume of bitumen absorbed by aggregates (vba)

⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎠⎞

⎜⎝⎛−⎟

⎠⎞

⎜⎝⎛×=

MVRcMVRMVavba 11100

MVRc is the mix's computed MVR. If the mass density measurement of aggregates is performed according to the French standard P 18-559 (i.e. measured using paraffin oil), the volume of bitumen absorbed would be zero, hence vba = 0.

Percentage of voids filled with bitumen (VFB)

%VMA%VbVFB 100=

where Vb is the volume of binder expressed as a percentage.


100100

100×

×+−××

=bext

ext

)TL()v(MVRTL

%Vbρ


100int

××

=VMA

MVAtlVFB bρ


- 40 -

⎟⎠⎞⎜

⎝⎛ ×+

×=

b

b

MVAtlv

MVAtlVFB

ρ

ρ

int

int

with: tlint "internal" binder content TLext "external" binder content MVA bulk density of the specimen

bρ density of the bitumen

v percentage of voids

gρ density of the mineral skeleton

LPC Bituminous Mixtures Design Guide - Type testing of bituminous mixtures -

- 41 -

2 TYPE TESTING OF BITUMINOUS MIXTURES

On the basis of a set of components (aggregates, fines, bituminous binders, mineral or organic additives), deemed representative of applicable materials, a series of laboratory tests is conducted to describe the behavior of a bituminous mixture. The specific tests have been chosen depending on the type testing level (from 1 to 4, the level 0 doesn’t include tests), required by the contract, potentially along with additional tests. This type testing level typically depends upon: the type of mixture, the position of the bituminous mixture layer in the pavement, its thickness, projected traffic levels, any special loadings (road ramps, interchanges, local temperature), the particular objective for applying this layer, the kinds of layers positioned beneath, and the scope of the given road-building works. A test protocol containing a sensitivity study may be required in order to verify that despite compositional variations in the mixture, the targeted characteristics will indeed be obtained. Type testing protocols have been stipulated in normative prescriptions included in former French product standard series NF P 98-130 through NF P 98-141, as well as in the general standard NF P 98-150-1 Bituminous mixtures, constituents, type testing, manufacturing, application and control. Most of these prescriptions are compatible with the current European product standards (EN 13108 – 1 to 7 and EN 13108-20 type testing) and have been included in the national foreword of the French version. In order to benefit from the experience gained on French bituminous mixtures types, taking into account the EN standardization, the designation of the bituminous mixtures types addressed in this Guide includes the EN designation followed by the French one. The most used products are listed and described in appendix F. Appendix E provides a summary table listing all specifications and designations based on the French experience, by type of mixture. For example for asphalt concretes AC according to EN 13108-1 (EB in the French version of EN), the following materials are addressed:

• AC-BBSG (Béton Bitumineux Semi-Grenu)

• AC-BBME (Béton Bitumineux à Module Élevé)

• AC-BBS (Béton Bitumineux pour chaussées Souples à faible trafic)

• AC-BBM (Béton Bitumineux Mince)

• AC-BBA (Béton Bitumineux Aéronautique)

• AC-GB (Grave-Bitume), Empirical and Fundamental

• AC-EME (Enrobé à Module Élevé). And in the same way, for the other types of materials:

• BBTM (Béton Bitumineux Très Mince) 7 The base series of the sieve is composed of the following elements (in mm): 0,063; 0,125; 0,250; 0,500; 1; 2; 4; 8; 16; 31,5.


- 42 -

• PA-BBDr (Porous Asphalt – Béton Bitumineux Drainant) Note that some of the prescriptions used to be normative in the former French standardization system. They now become informative as a French choice in the EN standards. The objective of this part of the guide is to compile the set of prescriptions, including the informative French choice, relative to: the components used, mix composition, test specimen preparation, and key material performance parameters. The used references are the following:

- Aggregates according EN 13043 and Standard XP P18-545, which is the French application guide for EN 13043,

- Reclaimed asphalt according EN 13108-8, - Binders according EN 12591, EN 13924 and EN 14023, - Bituminous mixtures, according EN 13108-2, -5, -7, - Type testing, according EN 13108-20, - Conditions concerning specimen preparation according test standards from

series EN 12697. At the end of this chapter, the requirements of European standards for initial type testing are presented in the form of summary tables.

2.1 Prescription relative to mix components

For some properties of the product undergoing qualification, due to the absence of a reliable enough method for identifying properties within the mixture, component-based prescriptions are imposed. Such is especially the case for durability properties when exposed to traffic, during the fabrication and implementation phases, as well as for surface characteristics.

2.1.1 Specifications regarding added fillers

The specifications issued on fillers have been set forth in Standard EN 13043. Among them, the following merit attention:

- Particle size distribution: lower limit and maximum range with the 0,125 mm and 0,063 mm sieves

- Harmful fines MBF (methylene blue test [EN 933-9]) - Voids of dry compacted filler V (Rigden void index [ EN 1097-4])

- Stiffening power Delta Ring and Ball ∆R&B [ EN 13179-1] - Additional prescription focusing on the Blaine specific surface [ EN 196-6],

meant to characterizing consistency of filler production. The two typical categories of fillers for such applications have been summarized in Table 1 below.


- 43 -

Table 1 – Typical filler characteristics for asphalt mixtures

Particle size criteria Sieve size (mm)

Harmful fines Stiffening properties

2 0,125 0,063

Passing Passing Range Passing Range

MBF, in g/kg

(Rigden)V, in

% ∆R&B, in

°C

≥ 100

85 to 100

≤ 10

≥ 70

≤ 10

≤ 10 MBF10

28 to 38 V28/38

8 to 16 denoted ∆R&B8/16

2.1.2 Specifications regarding fillers contained in the mixture

Product standards also contain specifications relative to either the fines from fine aggregate or mixed fillers (i.e. fines taken from fine aggregate and added fillers). The fines from fine aggregate or mixed fillers are extracted by means of dry sieving with the 0,125 mm sieve. These specifications have been recalled in Table 2. In the mixes produced at the plant, the fines for the most part stem not only from a fine aggregate with filler, but also from fine-particle aggregate at the surface of coarser aggregates and the fines produced by means of aggregate attrition during both the drying and mixing phases. Consequently, the fines from crushed aggregate must comply with Standard EN 13043, whose specifications are included in Table 2. An additional restriction pertains to the use of filler containing calcium hydroxide, which content must not exceed 1% within the mixture.

Table 2 – Specification on fines from fine aggregate or all-in aggregate or (in their absence) from mixed fillers

Characteristic MBF in g / 1000g

(Rigden)V in %

∆R&B in °C

Specification EN 13043

≤ 10 MBF10

28 to 38 V28/38

8 to 16 ∆R&B8/16

2.1.3 Specifications regarding fine aggregates or all-in aggregate (0/4, 0/6)

The fine aggregates used herein are either 0/2 (as defined in Standard EN 13043),or 0/4 all-in aggregate, for the majority of asphalt mixes. For AC-GB (Graves-bitume -dense asphalt concrete for base course), high modulus asphalt concrete (AC-EME) and “soft” asphalt concretes used on flexible pavements with low traffic loads (AC-BBS), the 0/6 fraction is acceptable. The fine aggregates 0/2 are sorted into category GF85 according to Standard EN 13043. They display 100% passing at the 4 mm sieve and between 85% and 99% at the 2 mm sieve. This set of characteristics corresponds to the code "a" defined in Standard XP P18-545, which is the French application guide for EN 13043.


- 44 -

The 0/4 and 0/6 all-in aggregates are of category GA85 (passing 100% at 2D, 98-100% at 1,4D, and 85-99% at D). The tolerances applied to the particle size distribution of both fine and coarse aggregate must respect the specifications associated with category GTC10 (±5% at D, ±10% at D/2, ±3% at 0,063 mm). The harmfulness of fine and coarse aggregate must be either MBF10 (as measured on the fines from fine aggregate) or MB2 (as measured on the 0/2 particle sizes) which is considered more severe than MB F10. The fines content from fine aggregate generally lies between 12% and 22%. Fine aggregates from category f16 or f22 can also be used, but in all cases, the fines content from fine aggregate must be specified through a declared value. The minimum angularity of fine aggregates (EN 933-6) is determined when the mixture is intended for surface courses. In general, this would apply to the categories ECS35 or 38, except in the case of “soft “ asphalt concrete AC-BBS (asphalt concrete used on flexible pavements with low traffic loads), for which ECS30 is accepted. For the other asphalt mixtures (used for the binder or base courses), angularity is not specified in the case where a wheel tracking test has been called for in the type testing protocol. Limiting the inclusion rate to just 10% of fine aggregate with round particles (declared ECS < 30) is accepted for the asphalt concrete for surface and binder course ( “Béton Bitumineux Semi Grenu” AC-BBSG), asphalt concrete for airfields (Béton Bitumineux aéronautique – AC-BBA), “soft” asphalt concrete (Béton Bitumineux Souple AC-BBS) and High modulus asphalt concrete for surface and binder course (Béton Bitumineux à module élevé – AC-BBME) categories. For asphalt concretes, a maximum value of fine aggregate friability (EN 932-3) is set at 40 for a 0/4 and at 45 for a 0/2. These specifications are not included any more in the product standards, however, they may be relevant and then can be verified.

2.1.4 Specifications regarding coarse aggregates

2.1.4.1 Physical requirements (Mechanical strength) and production characteristics

Both the minimum mechanical strength values and minimum production characteristics of coarse aggregates depend upon the position of the layer for which the mix is being designed as well as its thickness for surface courses. Production characteristics deal with grading, shape and fines content. Concerning the grading characteristics, the category GC85/20 [passing to D sieve between 85 % and 99 %, passing to d sieve between 0 % and 20 %, 100 % to 2 D sieve, 0 % to 5 % to d/2 sieve] is generally retained. For gap-graded mixtures, category GC85/15 may be necessary [passing to d sieve between 0 % and 15 %, instead of 20 % and for single size coarse aggregate D/d, where D/d < 2, which is the case for gap-graded mixtures used in surface course, passing to D sieve between 90 % and 99 %, 100 % to 2 D sieve, 0 % to 5 % to d/2 sieve]


- 45 -

The percentage passing at mid-size sieve [D/1,4], shall be between 25 % and 80 % for base course materials, and between 20% and 70% for binder and surface course materials, with in both cases, a tolerance on the typical grading of ± 15 %, declared by the producer, that means categories respectively G25/15 and G20/15. The shape of coarse aggregate is determined in terms of the flakiness index FI. FI25 is the generally retained category. For very thin layers intended mixtures, category FI20 may be necessary. The fines content of coarse aggregate is measured by the percentage of passing at 0,063 mm sieve. Category f1 is used [≤ 1 % at 0,063 mm sieve], for common uses and category f0,5 for very thin layer intended materials. An overview of these characteristics is given in table 3.


- 46 -

Table 3 – Indicative minimum characteristics of coarse aggregates :

Mechanical strength and production characteristics

The minimum values, as indicated in bold characters, extracted from Standard EN 13043, correspond to classifications either less than or equal to the minima transposed from the former French aggregate standards. The italic values correspond to the French application of aggregate standards as described in XP P 18-545.

Type of use Mechanical strength

EN 13043 XP P 18-545

Production characteristics

Lower base layer LA40 MDE35 LA40 MDE35

(1)

GC85/20 G25/15

FI25 f1

Upper Base layer LA30 MDE 25 LA30 MDE 25

(1)

GC85/20 G25/15

FI25 f1

Thick binder layer (≥ 5cm)

LA30 MDE 25 LA30 MDE 25

(1)

GC85/20 G20/15

FI25 f1

Thin binder layer (AC-BBM) LA25 MDE 20 LA25 MDE 20

(1)

GC85/20 G20/15

FI25 f1

Thick surface course and lightweight airfield pavements

LA25 MDE 20 PSV MDE 50 LA25 MDE 20

(1)

GC85/20 G20/15

FI25 f1

Thin surface course (BBTM and Porous Asphalt PA-BBDr) and heavy airfield pavements

LA20 MDE15 PSV50

(2)

LA20 MDE15(1)

GC85/15 (gap-graded grading)

GC85/20 G20/15

FI20 f0,5

(1) With any potential application, when justified and given an explicit justification within the materials contract documents, a

maximum compensation of 5 points between the LA and MDE characteristics (see XP P 18-545). For example: ⎯ an aggregate with LA = 25 is deemed compliant with [LA20, MDE15] if it exhibits an MDE value of 10

⎯ an aggregate with MDE = 20 is deemed compliant with [LA20, MDE15] if it exhibits an LA value of 15

⎯ an aggregate with MDE = 18 is deemed compliant with [LA20, MDE15] if it exhibits an LA value of 17 (2) For a number of unique points, it becomes necessary to predict the PSV53 (declared) value, or even the PSV56 value.

2.1.4.2 Particle size distribution

For coarse aggregates, the usual grading fractions are: 2/4, 2/6, 4/6, 4/10, 6/10 and 10/14. For mixes intended in applications as road base, the fractions 2/10, 6/14, 6/20, 10/20 and 14/20 may also be used. The possible D values for each type of mixture are displayed in Table 4.


- 47 -

Standard EN 13043 imposes using the base series + series 2 sieve or the base series + series 1 sieve. It is common practice to opt for the base series + series 2 sieve.

Table 4 – Accepted values of D vs. type of mixture

Asphalt mix D, expressed in mm

Asphalt concrete for surface and binder course (AC-BBSG)

High modulus asphalt concrete for surface and binder course (AC-BBME)

Asphalt concrete for surface and binder course for airfield (AC-BBA)

Thin layer asphalt concrete A or B type (AC-BBM type A or B)

10 - 14

Graves-bitume (Asphalt concrete for base) (AC-GB) 14 - 20 (2)

High modulus asphalt concrete for base course (AC-EME) 10 - 14 - 20 (2)

Thin layer asphalt concrete C type ( AC-BBM type C) 10

Very thin layer asphalt concrete (BBTM), Porous asphalt (PA-BBDr) 6 - 10 (1)

(1) It is possible to use the 8-mm sieve (European standard). (2) It is possible to use the 16-mm sieve (European standard).

The type A thin layer asphalt concretes (AC-BBM type A) are characterized by a discontinuity between 2 and 6 mm, while the type B (AC-BBM type B) are characterized by a discontinuity between 4 and 6 mm. The type C (AC-BBM type C) mix designs are of a continuous grading.

2.1.4.3 Angularity

The angularity of coarse aggregates exerts a sizable impact on the surface course with respect to texture, which is why this characteristic must always be taken into account for mixes designed with this purpose. The angularity of coarse aggregates is measured in accordance with Standard EN 933-5 guidelines. The aggregates derived from crushed rock are considered to lie in category C100/0. Coarse aggregates from alluvial deposit extraction for use on surface courses must be of category C95/1. For some “soft” asphalt concretes types (AC-BBS) submitted to low traffic levels, coarse aggregates of category C50/10 could also be employed.

2.1.5 Specifications regarding additives

No distinct specification has been incorporated into the standards.


- 48 -

The term additives encompasses adhesion agents – for which the potential degradation when exposed to temperature has been indicated [NF P 98-150-1] – as well as organic and mineral additives intended to modify the physical and mechanical characteristics of asphalt mixes. It has to be pointed out that according to EN 13108 series, only constituent materials with established suitability shall be used. The establishment of suitability shall result from one or more of the following: European Standards, European Technical Approval (ETA), specifications for materials based on demonstrable history of satisfactory use in asphalt. Evidence shall be provided on their suitability. This evidence may be based on research combined with evidence from practice. In the European asphalt industry, it is common practice to use additives like inorganic or organic fibers, pigments, waxes, etc, which are not covered by European standard or ETA. The European product standards allow the use of those materials. It should be pointed out that the content of an adhesion agent is equal to the mass of the agent as a ratio of binder mass, expressed as an external percentage or per-thousand. The content of additives (other than adhesion agents) may be expressed as the additive mass as a ratio of dry aggregate mass, expressed as an external percentage or as a ratio of mixture mass, expressed as an internal percentage. Additives are to be incorporated at the time of the mixing operation.

2.1.6 Specifications regarding binders

For all asphalt mixes, the choice lies between paving grade bitumen, in compliance with EN 12591, polymer-modified bitumen and special bitumen, with the objective being to derive the prescribed level of mix performance. In the case of prescribed polymer-modified bitumen performance, no codified specification is in fact available. The standard EN 14023 is confined to just a single classification. Nevertheless two types of polymer-modified bitumen are usually specified according to a minimum plasticity interval, defined by difference between the softening point and Fraass temperature, and the level of maximum Fraass temperature. The first criterion shows degree of modification, high degree for class 4 > 75°C and low degree for class 6 > 65°C. The second criterion depends on local climate conditions, for example class 5 (Fraass temperature < -10°C) or class 7 (Fraass temperature < -15°C).

With respect to hard grade bitumen, these specifications have been included in the standard EN 13924. The French recommended binders in the National annex are 10/20 with a ring and ball range from 60°C to 76°C and 15/25 with a ring and ball range from 55°C to 71°C. The supplier shall declare a reduced softening point of ± 5°C around the central point. The resistance to hardening using RTFOT test is class 2 (mass variation < 0,5%, increase of softening point < 8°C, remaining penetrability > 55%). In the case of recycled mixes and for recycling rates over 10% for surface courses and over 20% for binder courses and bases , it has been stipulated in EN 13108 series that the added binder is a pure bitumen, which makes the level of penetration P or the softening point TR&B resulting from the combined binder well adapted to the desired end use. The mixture rules can then be applied to penetration as follows:


- 49 -

lg(P) = a lg (P1) +b lg (P2) where a and b are the respective proportions of binders, P1 being the penetration of the binder recovered from the reclaimed asphalt and P2 the penetration of the added binder.

TR&Bmix = a TR&B1 +b TR&B2 where a and b are the respective proportions of binders, TR&B1 being the softening point of the binder recovered from the reclaimed asphalt and TR&B2 the softening point of the added binder. When natural asphalt is added, it shall comply with Annex B of EN 13108-4 requirements. Two categories are defined: High ash and Low ash content. For the first category, the penetration at 25°C, shall be between 0 and 4 1/10 mm, the softening point between 93 and 99 °C, the solubility between 52 and 55%, the ash content between 35 and 39% by mass and the density between 1,39 and 1,42 g/ml. For the second category, the penetration at 25°C, shall be between 0 and 1 1/10 mm, the softening point between 160 and 182 °C, the solubility greater than 95%, the ash content between 0 and 2% by mass and the density between 1,01 and 1,09 g/ml.

2.1.7 Specifications regarding reclaimed asphalt These specifications are described in EN 13108-8. The reclaimed asphalt is designated by the abbreviation RA preceded by the asphalt particle size designation U and followed by the aggregate size designation d/D in mm. U is the smallest sieve size in mm trough which 100% of the asphalt particles pass. For RA, d will almost invariably be 0. D is the larger of:

- the sieve M/1,4, where M is the smallest sieve with 100% passing, - the smallest sieve with 85% passing.

The reclaimed asphalts are classified in terms of foreign matter content. Usually the category used is F1 corresponding to materials containing less than 1% of group 1 foreign matters (cement concrete, bricks, cement mortar, metal) and less than 0,1 % of group 2 foreign matters (synthetic materials, wood, plastics). The reclaimed asphalt capable of being reused exhibit an apparent U (particle size of reclaimed asphalt) value of less than or equal to 35 mm. The upper sieve size D of the aggregate in reclaimed asphalt shall not exceed the upper sieve size D of the mixture to be produced. The aggregate properties of the reclaimed asphalt shall fulfill the requirements for the aggregate for the mixture (history may be accepted). When using more than 10 % by mass of the total mixture of reclaimed asphalt for surface courses or more than 20 % for other courses, in which only paving grade bitumen has been used, and when the binder added is a paving grade and the grade of the bitumen of the mixture is required, the binder shall conform to the following requirement: Penetration or softening point of the binder in the resulting mixture, calculated from the penetrations or the softening points of the added and the recovered binder from reclaimed asphalt shall meet the penetration or softening point requirements of the selected grade. Either the penetration or the softening point has to be considered.


- 50 -

The calculation is described in Annex A of each standard from EN 13108 series and in clause 2.1.6. When the feedstock contains mainly reclaimed asphalt with paving grade bitumen, reclaimed asphalt are categorized as P15, if the binder of each of the sample is at least 10 1/10 mm and the mean penetration of all samples is at least 15 1/10 mm or it is categorized as S70 if softening point of each of the samples is not greater than 77°C and the mean softening point of all of the samples is not greater than 70°C. For other reclaimed asphalt category Pdec or Sdec means the mean penetration or the mean softening point of all samples. It would be beneficial to distinguish the reclaimed asphalts of various sources from those that have undergone a generally complete identification (either by testing or by history) with respect to binder content and homogeneity, as well as the residual properties of the recovered binder and aggregate characteristics. It is acknowledged that reclaimed asphalts from the first category may be used at a rate of 10% in mixes not destined for surface courses. Reclaimed asphalts belonging to other categories may be recycled as wearing course components and, depending on the specific circumstances, at higher recycling rates. For both porous asphalts, PA, and very thin layer asphalt concretes, BBTM, however, the inclusion of reclaimed asphalts is not recommended. For thin asphalt concretes of the A or B type, as a default precaution reclaimed asphalts are not authorized. The French standard application guide includes a table about the reuse rate of reclaimed asphalt versus the use and the degree of knowledge of the material, this table is coming from the former French Standard XP P98-135 Reclaimed asphalt. The reclaimed asphalt characteristics to be identified for reuse purposes have been summarized in Table 5 below:


- 51 -

Table 5 – Reclaimed asphalt characteristics vs. reuse rate

Type of layer Reuse rate (%)

Surface course 0 0 10 subject to (1) 30 40

Binder layer 10 20 30 40

Use

in th

e pa

vem

ent

Base course 10 20 30 40

Binder content Range Unspecified ≤ 2% ≤ 1% Penetrability

1/10 mm ≥ 5 ≥ 5

Penetration range – ≤ 15

R&B °C ≤ 77 ≤ 77

Asphalt binder

Residual characteristics

(penetration or Softening point)

R&B range

Unspecified

– ≤ 8

Passing at D

Range

80 - 99

≤ 15

85 - 99

≤ 10 Range of

2-mm passing

≤ 20 ≤ 15 Particle size distribution

Range of 0,063 mm passing

Unspecified

≤ 6 ≤ 4

Category Unspecified For example LA20,MDE20

Info

rmat

ion

on re

clai

med

asp

halt

com

pone

nts

Aggregates

Intrinsic characteristics

Angularity – C90/1

(1) If the average external binder content of the reclaimed asphalt exceeds 5,5%, it is then considered that the mix is an asphalt concrete whose aggregates have been selected on the basis of minimum criteria in the vicinity of the criteria sought for the recycled material. Nevertheless no limestone aggregate should be used as surface course.

2.2 Specifications regarding mixture composition

2.2.1 Grading

The particle size distribution curve is not specified in the French standard. Nevertheless overall limits of target composition are required (grading envelope) for 0,063 mm, 2 mm, D and 1,4 D sieves. Pertinent specifications have been listed in Table 6.


- 52 -

Table 6 – Overall limits of target composition

Asphalt mix 0,063 mm sieve

passing in %

2-mm sieve passing,

in %

D in %

1,4 D in %

AC10 2,0 to 12,0 10 to 60 90 to 100 100

AC14 0,0 to 12,0 10 to 50

10 to 60 for airfields

90 to 100 100

AC20 0,0 to 11,0 10 to 50

10 to 60 for airfields

90 to 100 100

BBTM6A 7,0 to 9,0 (11) 25 to 35 90 to 100 100

BBTM6B 4,0 to 6,0 15 to 25 90 to 100 100

BBTM10A 7,0 to 9,0 25 to 35 90 to 100 100

BBTM10B 4,0 to 6,0 15 to 25 90 to 100 100

PA-BBDr 2,0 to 10,0 5 to 25 90 to 100 100

2.2.2 Binder content and Richness Modulus In the former French system, the binder content was based on the concept of “Richness Modulus”, whose approach is close to the thickness of the bitumen foil and which makes the requirement independent from the grading curve of the mixture. In order to conform to EN 13108 series which doesn’t deal with this concept, the requirements have been translated in “binder content”. In the case of empirical approach, a Bmin value is given for each type pf material, in the case of fundamental approach , the minimum binder content is fixed at 3,0%. Nevertheless, to keep for reference this concept, the richness modulus is mentioned in parallel with the minimum binder content in table 7.


- 53 -

Table 7 – Minimum Binder content and richness modulus values

Asphalt mix Minimum binder

content % Empirical Fundamental

Minimum richness modulus

K AC10-BBSG Bmin5,2 3,0% 3,4

AC14-BBSG Bmin5,0 3,0% 3,2

AC10-BBA C (Continuous) Bmin5,4 3,0% 3,6

AC14-BBA C (Continuous) Bmin5,2 3,0% 3,5

AC10-BBA D (Discontinuous) Bmin5,2 3,0% 3,4

AC14-BBA D (Discontinuous) Bmin5,0 3,0% 3,2

AC10-BBM Bmin5,0 - 3,3

AC14-BBM Bmin5,0 - 3,2

PA6-BBDr class 1 Bmin4,0 - 3,4



PA10-BBDr class2 Bmin4,0 - 3,1

BBTM6 Bmin5,0 - 3,5

BBTM10 Bmin5,0 - 3,4

AC-GB class 1 1 (Bmin3,4) - --

AC-GB class 2 Bmin3,8 3,0% 2,5

AC-GB class 3 Bmin4,2 3,0% 2,8

AC-GB class 4 2 - 3,0% 2,9

AC-EME class 1 2 - 3,0% 2,5

AC-EME class 2 2 - 3,0% 3,4

AC10-BBME 2 - 3,0% 3,5

AC14-BBME 2 - 3,0% 3,3

Note 1: GB1 was not considered in the last version of French Standardization.

Note 2: Due to the fundamental approach, the minimum binder content is not specified. 3% is a bottom rate of the EN 13108-1 for all types of asphalt concretes described by the fundamental approach.

2.3 Preparation of test specimens

2.3.1 Density measurements

The maximum density ρmv (MVR in French documents) is measured directly on the mixture (hot-mixing of 1,5 kg, in compliance with the formula) using the "A" method "with water" described in EN 12697-5 (average of 3 replicas). This method is the reference method in EN 13108-20 for the void content determination of the specimens and for the gyratory compaction test. This method offers the advantage of being implemented on the total mixture, which allows reducing the number of tests to be performed, in comparison with the


- 54 -

calculation method based on the maximum density of each granular fraction. When refining the mix design, in the aim of varying component proportions, the method may be practiced on each one of the granular fractions, after mixing with a known bitumen concentration. The maximum density ρg of the granular fraction, mixed in at a bitumen content of TLext or tlint, is thus given by the following relations:

⎟⎟⎠

⎞⎜⎜⎝

⎛−+

=

b

extg MVRTL

MVR

ρ

ρ1

1001

b

g tlMVR

tlMVR

ρ

ρint

int

100

)100(

−

−=

where ρb is the maximum density of the binder. The MVR derived according to this approach serves as a basis not only for calculating the void percentages of specimens submitted to evaluation within the scope of this type testing, but also for conducting in situ measurements. In the former French system, the maximum density of aggregates was measured in accordance with the standard P 18-559 using paraffin oil featuring a viscosity close to that of bitumen during the mixing operation. The maximum density MVR of the mixture could then be calculated by applying the following formula (binder content is “out” of the mixture):

b

ext

gn

n

gg

ext

TLG%....G%G%TL

MVR

ρρρρ++++

+=

2

2

1

1

100

where %Gi are the granular fraction percentages and ρi their respective maximum densities. This method, which was mandated in the "product" standards, makes it possible to overcome the notion of absorbed bitumen for aggregates displaying a certain amount of porosity. Moreover, by making reference to a single method for determining MVR, the subsequent measurements of void percentage can be more easily compared. A joint USIRF (French Road Industry organization) / RST (French state Laboratories) working group has demonstrated that a very strong correlation was found between MVR measured directly on the mixture with water and that calculated using the paraffin oil-based method for each of the garnular fractions.

2.3.2 Procedure for reheating and incorporating mix reclaimed asphalts

The European standard addresses the incorporation of reclaimed asphalts; once pulverized, the reclaimed asphalts are weighed to within 0,1%, at the prescribed rate levels:

⎯ Case of reclaimed asphalts reheated prior to incorporation at the plant: they are reheated up to the recommended temperature ± 5°C, by means of a hopper fitted with ventilation, and then placed in an oven at the designated preparation temperature for 2,5 ± 0,5 hours.The hopper must be periodically shaken in order to avoid excess pressure buildup.


- 55 -

⎯ Case of reclaimed asphalts not reheated prior to incorporation at the plant: they are reheated to 110 ± 5°C, by means of a ventilated oven, for 2,5 ± 0,5 hours. It is possible to overheat the unmixed aggregate compared to the standard temperature vs. reclaimed asphalt concentration.

When using paving-grade bitumen, mixing times get increased by 1 min.

2.3.3 Mixing

The mixtures are produced in accordance with EN 12697-35. In the EN standard, the added filler is included either with the aggregates or after introducing the bitumen. It is customary to opt for the former. As opposed to the specifications listed in the former French standard, the European standard does not address the overheating of aggregates if the mixer has not been equipped with a thermo-regulated tank.

2.3.4 Compaction of test specimens For water resistance tests, specimens are either compacted using the gyratory compactor or in the form of cored samples extracted from plates produced using the slab compactor. However, when using EN 12697-12, part B (Duriez test), it is necessary to compact specimens using double static compression described in part B, in order to compare the obtained results with the former NF P 98251-1 (Duriez test). For mechanical tests, the plates are also generated with the slab compactor, as specified in EN 12697-33, at a targeted level of compacity. The use of a plate or plank at the completion of compaction, in order to improve the state of the plate surface, is not allowed since the impact on the wheel tracking test result has already been shown.

2.3.5 Test specimen sawing and bonding

Cylindrical or trapezoidal test specimens are sawn and bonded as prescribed in the standard NF P 98-250-3 guidelines. This point has not been addressed in the European standards.

2.3.6 Test specimen conservation

For the ITSR water resistance test, specimens must undergo a minimum storage of 16 hours between specimen production and the beginning of conservation. For a wheel tracking test, it is necessary to set aside at least 2 days between the end of compaction and preparation on the rutting tester (EN 12697-22). For a fatigue or stiffness test, the time lag between coring or sawing and test initiation amounts to between 2 weeks and 2 months.


- 56 -

2.3.7 Test specimen void percentage

The test specimens intended for use in either wheel tracking or mechanical tests (stiffness or fatigue) must satisfy a number of specifications concerning void percentages. The void percentage may be determined on the slab using a gamma bench, as set forth in standard EN 12697-7 through a three-level operation. Should such a set-up not be available, void percentages are to be measured using the geometric method either on the slab for wheel-tracking tests or on the samples for stiffness or fatigue. Common values are listed in Table 8 below.

Table 8 – Test specimen characteristics

Wheel tracking tests (large device)

Fatigue / stiffness modulus

Slab thickness

(mm)

Void percentage (%)

Slab thickness

(mm)

Void percentage (%)

AC-BBSG and AC-BBME 100 5 to 8 120 5 to 8

AC-BBM class A 50 7 to 10

AC-BBA (except AC10-BBA D) 100 4 to 7 120 4 to 7

AC10-BBA D 50 4 to 7 120 4 to 7

AC-BBM class B or C 50 8 to 11

AC-GB class 2 100 8 to 11 120 7 to 10

AC-GB class 3 100 7 to 10 120 7 to 10

AC-GB class 4 100 5 to 8 120 5 to 8

AC-EME class 1 100 7 to 10 120 7 to 10

AC-EME class 2 100 3 to 6 120 3 to 6

BBTM10 50 9 to 16

BBTM6 50 16 to 22

The bulk density of the two specimens used to measure the

rut depth shall not deviate by more than ± 1% of the mean

bulk density

2.4 Execution of type testing Depending upon the intended use, the type of asphalt mix and loadings, requirements may differ. For this reason, type testing is divided into several levels extending from 0 to 4, and complemented for certain materials or uses by additional tests.

2.4.1 Choice of test typing level Level 0, which has been introduced into the French foreword of the standards and also in NF 98-150-1 corresponds to a description of the mixture according to grading


- 57 -

and binder content, that means without any further test. It is used for mixtures intended to non-trafficked areas. The other various testing levels vary from the simplest (level 1) to the most thorough (level 4), with the higher levels always encompassing the requirements addressed in the lower levels. A description of contents for each level along with the reasons behind the corresponding choice will be provided in the following sections 2.4.2 through 2.4.5. The level 0, without test is not described. According the definitions of EN 13108-1, level 0, level 1 and level 2 are relevant of the general + empirical approach and level 3 and level 4 of the general + fundamental one. Level 4

Figure 18: Summary diagram of the various type testing levels

2.4.2 Level 1

The mixture must be able to satisfy a full range of void percentages for use in the Gyratory Compactor test (see Section 1.3.1) as well as the water resistance threshold (Section 1.3.2).

Niveau

Niveau

Niveau Niveau

Niveau Niveau

Orniérage

Modul

Fatigu

Wheel tracking

Stiffness modulus

Fatigue

Gyratory compactor : Water resistance

Gen

eral

+

Em

piric

al

Gen

eral

+

Fund

amen

tal

Level 3

Level 4

Level 0

Level 2

Level 1


- 58 -

Except for non trafficked areas, this level would be common to all testing protocols. In the case of applications at low loading rates, level 1 may be sufficient without the need for any further test. The water-sensitivity is measured according EN12697-12, method B in compression. Remark: For some materials, a void percentage requirement at 10 gyrations for the Gyratory Compactor test needs to be met. This requirement has been addressed in the European standards, yet merely from the standpoint of an "empirical" specification with respect to wheel tracking resistance. It is then not allowed to specify, at the same time, both rutting tester results and the void percentage after 10 gyrations as it is considered as an over-specification.

Table 9 – Specifications relative to the void percentage

Gyratory Compactor specifications after n gyrations

Type of mix Number of

gyrations (n)

Void percentage (%)

Specification after 10 gyrations (%)

AC10-BBSG 60 5 to 10 Vmin5- Vmax10

AC14-BBSG 80 4 to 9 Vmin4- Vmax9 ≥ 11 V10Gmin11

AC10-BBME 60 5 to 10 Vmin5- Vmax10

AC14-BBME 80 4 to 9 Vmin4- Vmax9 ≥ 11 V10Gmin11

BBTM6 class A 12 to 20 Vmin12- Vmax20

BBTM6B 21 to 25 Vmin12- Vmax25

BBTM10A 10 to 18 Vmin10- Vmax18

BBTM10B

25

19 to 25 Vmin19- Vmax25

_

AC-BBM class A 6 to 11 Vmin6- Vmax11

AC-BBM class B 7 to 12 Vmin7- Vmax12

AC-BBM class C

40

8 to 13 Vmin8- Vmax13

≥ 11 V10Gmin11

40 20 to 25 Vmin20- Vmax25 PA-BBDr class 1 200 > 15 Vmin15

40 25 to 30 Vmin25- Vmax30 PA-BBDr class 2 200 > 20 Vmin20

_

AC10-EME class 1 < 10 Vmax10

AC10-EME class 2 80

< 6 Vmax6

AC14-EME class 1 < 10 Vmax10

AC14-EME class 2 100

< 6 Vmax6

AC20-EME class 2 120 < 6 Vmax6

_

AC14-GB class 2 < 11 Vmax11


AC14-GB class 4

100

< 9 Vmax9

>14 V10Gmin14


- 59 -

Gyratory Compactor specifications after n gyrations

Type of mix Number of

gyrations (n)

Void percentage (%)

Specification after 10 gyrations (%)



AC20-GB class 4

120

< 9 Vmax9

Surface: 3 - 7 Vmin3- Vmax7 > 10 V10Gmin10

AC10-BBA C 60 Binder:

4 - 8 Vmin4- Vmax8 > 11 V10Gmin11

Surface: 3 - 7 Vmin3- Vmax7 >10 V10Gmin10

AC14-BBA C 80 Binder:

4 - 8 Vmin4- Vmax8 >11 V10Gmin11

AC10-BBA D 40 5 to 9 Vmin5- Vmax9 > 9 V10Gmin9

AC14-BBA D 60 5 to 9 Vmin5- Vmax9 >10 V10Gmin10

Table 10 – Specifications relative to water resistance

Type of mix ITSR (I/C)

(%) Method B in compression

AC-BBSG ITSR70

AC-BBME ITSR80

AC-BBA surface course ITSR80

AC-BBA binder layer ITSR70

PA-BBDr ITSR80

BBTM ITSR80

AC-BBM ITSR70

AC-EME ITSR70

AC-GB ITSR70


- 60 -

2.4.3 Level 2

This level comprises the Level 1 tests (Gyratory Compactor and water resistance) and adds a wheel tracking, or resistance to rutting, test.

Table 11 – Specifications relative to the wheel tracking test

Type of mix Class Number of cycles Specification, in % rutting

(large device)

1 ≤ 10% P10

2 ≤ 7,5% P7,5 AC-BBSG AC-BBME

3

30000

≤ 5% P5

1 ≤ 10% P10

2 ≤ 7,5% P7,5 AC-BBA 3

10000

≤ 5% P5

1 3000 ≤ 15% P15

2 10000 ≤ 15% P15 AC-BBM 3 30000 ≤ 10% P10

BBTM10 1 and 2 ≤ 15% P15

BBTM6 1 and 2 3 000

≤ 20% P20

2 and 3 10 000 ≤ 10% P10 AC-GB

4 30 000 ≤ 10% P10

AC-EME 1 and 2 30 000 ≤ 7,5% P7,5

2.4.4 Level 3

This level contains the Gyratory Compactor and water resistance tests of level 1, the wheel tracking test of level 2, and includes the step of characterizing the mixture's stiffness modulus. The stiffness test has been specified within the context of major road-building works and whenever the targeted layer is involved in the structural function of the pavement. This level means that the product is considered in the Fundamental approach of EN standard. The stiffness value at 15°C, 10 Hz or 0,02s is directly used in the structural design models. Due to their main characteristic, the type testing of AC-GB class 4, AC-BBME and AC-EME mixes must imperatively comprise a stiffness test. For other bituminous mixtures, which are subject to be empirical or fundamental, it may be required.


- 61 -

Table 12 – Specifications relative to the stiffness modulus

Type of mix Class Stiffness modulus at 15°C,

10Hz or 0,02 sec (MPa)

1 5 500 S5500 AC-BBSG Fundamental Approach 2 and 3 7 000 S7000

1 9 000 S9000 AC-BBME

2 and 3 11 000 S11000

2 and 3 9 000 S9000 AC-GB Fundamental Approach 4 11 000 S11000

AC-EME 1 and 2 14 000 S14000

1 and 2 5 500

S5500

AC-BBA Fundamental Approach

3 7 000

S7000

2.4.5 Level 4

This level encompasses the Gyratory Compactor and water resistance tests from level 1, the wheel tracking test from level 2 and level 3 stiffness modulus characterization of the mixture; it is duly completed by a determination of fatigue resistance. As level 3, this level is relevant of the Fundamental approach. The fatigue test is to be specified in the case of large-scale jobs and once the targeted pavement layer is submitted to fatigue. The ε6 value is directly used in the structural design models. AC-BBME and AC-EME are of course relevant of the fundamental approach. For other bituminous mixtures, which are subject to be empirical or fundamental, it may be required.

Table 13 – Specifications relative to fatigue resistance

Type of mix Class

Fatigue specification, ε

6 10°C, 25 Hz Annex A – 2 points trapezoidal

AC-BBSG

Fundamental Approach 1 to 3 ε6-100

1 ε6-100

AC-BBME 2 and 3 ε

6-100

AC-GB 2 ε6-80


- 62 -

3 ε6-90

4 ε6-100

1 ε6-100

AC-EME 2 ε

6-130

1 ε6-130

2 ε

6-115

AC-BBA Fundamental Approach

3 ε6-100

2.4.6 Additional tests

- For porous asphalts, EN 13108-7 contains a specification on the vertical or horizontal permeability according to EN 12697-19; the values extend from 0,1 mm/s to 4 mm/s for both the horizontal permeability Kh and vertical permeability Kv. The drainage tests (EN 12697-18) are also addressed in this standard. The specifications focusing on the abrasion test for porous asphalt mixes (EN 12697-17) are considered as not relevant. - For mixes used on airfield runways/taxiways, the resistance to the effect of fuels can also be prescribed (EN 12697-43), as can the resistance to deicing fluids (EN 12697-41).

2.5 Formula verification

This step is to be performed to validate an existing formula if the asphalt mix design has been performed at least at level 1 of the type testing routine. The material origin, particle size distribution curve and bitumen content are all considered to remain unchanged. For aggregates however, it is distinctly possible that shape variations for example, imperceptible using typical means of measurement (bulk density, particle size grading curve, etc.), exert a significant impact on material behavior. The verification protocol consists of conducting the most selective type of tests possible in order to detect these changes or, instead, to verify the persistence of characteristics inherent in the studied mixture. The most common test is that using the Gyratory Compactor. The selected criterion is the identity of the entire curve at ±1,5%. As a general rule, this criterion is sufficient for confirming that the mix design has not been altered by major changes. The other characteristics (wheel tracking resistance, stiffness modulus, etc.) are thus considered to be valid provided the bitumen used matches that of the reference case. Any change in bitumen must trigger a new verification of these characteristics. It could be worthwhile to measure, in specific cases, the characteristic targeted for verification: e.g. wheel tracking resistance on a mix specially designed for this purpose, by means of the stiffness modulus for a material with a high modulus.


- 63 -

2.6 Type testing procedure length and required quantity of materials

Performing a type testing protocol requires a good ten days or more for level 1, with 60 kg of materials and roughly a month to reach level 4, with a total material supply weighing 400 kg. The amount of time needed for the tests level by level are indicated in Table 14; the estimations shown have been derived by assuming the measurement of the maximum density according EN 12697-5 method A in water and the compression test (method B of EN 12697-12) for water resistance.

Table 14 – TYPE TESTING Required material quantities – Approximate testing durations

Duration Level Test name Quantity of

material Test Preparation and ancillary operations

Total duration (including

preparation)

Preparation Maximum density of the mixture

5 kg for the mixture 1 day drying + test 2 days

Identification of components

Particle size analysis

3 kg per particle size fraction 1 day drying + test 2 days

ITSR test

Method B in compression

20 kg (Φ 80 mm)

40 kg (Φ 120 mm)8 days drying + mixture + test 10 days

1

Gyratory Compactor 30 kg 1 day drying + mixture + test 2 days

Total - Level 1 40 - 60 kg 12 days

2 Wheel tracking

Large device (2 Slabs) 50 kg

2 plates 30,000 cycles - 3

days

sample production + storage + V% + test 7 days

Total - Level 2 110 kg 15 days

Modulus by direct tensile test (Annex E)

80 kg 3 temperatures

3 or 4 loading times 4 days

sample production + coring/storage + V%

+ bonding + test 21 days

3 Complex modulus 80 kg

1 temperatures 1 frequencies

1 day

sample production + sawing/storage + V%

+ bonding + test 18 days


4 Fatigue 200 kg 15 days sample production +

sawing + storage + V% + bonding + test

25 days



- 64 -

2.7 Summary of test characteristics and methods

The selected tests and testing procedures included within the scope of the type testing of asphalt mixes found in EN standards have been laid out in Standard EN 13108-20, " Material specification - Type testing". They will be displayed in the following tables by family of mix. The highlighted procedures correspond to the most widely practiced at the present time.

2.7.1 Asphalt mixes

These are listed in the standard (EN 13108-1) and encompass the types AC-BBSG, AC-BBME, AC-BBS, AC-BBM, AC-BBA, AC-GB, AC-EME.

Table 15 – Types of tests for asphalt mixes

Characteristic Testing method Observations

Binder content

(prescriptive)

EN 12697-1, Soluble bitumen content

and EN12697-39, Bitumen content by ignition

When type testing is performed with laboratory-made materials, the bitumen content considered is the quantity of bitumen incorporated into the mixture. On the other hand, when testing is conducted with materials extracted from the plant, the binder content of the mix is determined by using one of these methods.

Grading - Particle size distribution (prescriptive)

EN 12697-2, Particle size distribution

Method not employed in the case of type testing performed in the laboratory (see above).

Void percentage, including voids filled by bitumen and voids in mineral aggregate, void content Vmax ≤ 7%

(prescriptive)

EN 12697-8, Determination of void characteristics of bituminous specimens Apply EN 12697-6 (bulk density), Method B, dry saturated surface Apply EN 12697-5 (maximum density - MVR), Method A in water

Specifications on the void percentage pertain specifically to measurements conducted on test specimens within the scope of a type testing procedure. For example, the void percentage of impact-compacted "Marshall" specimens must be determined in this manner.

Void percentage, including voids filled by bitumen and voids in mineral aggregate, void content 7 < Vmax < 10%

(prescriptive)

EN 12697-8, Determination of void characteristics of bituminous specimens Apply EN 12697-6 (bulk density), Method C, paraffin-sealed Apply EN 12697-5 (maximum density - MVR), Method A in water

See above.

Void percentage, including voids filled by binder and voids contained in the granular skeleton, void content Vmax ≥ 10%

EN 12697-8, Determination of specimen void percentage Apply EN 12697-6 (bulk density), Method D by dimensions

See above.


- 65 -


Apply EN 12697-5 (maximum bulk density - MVR), Method A in water

Void percentages by Gyratory Compaction(prescription)

EN 12697-31, Gyratory Compactor test

This test standard includes a determination of the void percentage based on measurement of the specimen height, which makes this method applicable.

Sensitivity to water (performance-related)

EN 12697-12, Sensitivity to water

Method B (compression test) shall be used in France, even the result is noted ITSR.

Resistance to abrasion caused by studded tires (performance-related)

EN 12697-16, Method A

Resistance to permanent deformation (performance-related: for roads(a))

For asphalt mixes designed for axle loads < 13 T

EN 12697-22, small device, Method B in air at a specified temperature


For asphalt mixes designed for axle loads ≥ 13 T

EN 12697-22, large device, in air at a specified temperature

This reference corresponds to the LPC device and set-up. In selecting a temperature of 60°C and a number of cycles equal to 3000, 10000 or 30000, the specifications are identical to those of the former French standard.

Resistance to permanent deformation (performance-related: for airport runways/taxiways(b))

EN 12697-34, Marshall test The resistance to wheel tracking is characterized empirically (by creep) using the Marshall test and not the wheel tracking test for airport-designed asphalt mixes.

Resistance to permanent deformation (performance-based)

EN 12697-25, Triaxial compression test

Stiffness modulus (performance-based)

EN 12697-26, Stiffness modulus

All procedures for determining the stiffness modulus are considered to be equivalent. Nonetheless, these specifications address moduli at 15°C, 10 Hz or 0,02 sec. Some equipment is not capable of yielding stiffness modulus values for these loading times or frequencies.

2-point fatigue (performance-based) for the design of pavements derived from 2-point fatigue

EN 12697-24, Fatigue resistance – Annex A

Appendix A describes the fatigue test in 2-point bending as compatible with the design method applied in France. The specifications at 10°C / 25 Hz are identical to those cited in the former reference.

4-point fatigue (performance-based) for

EN 12697-24, Fatigue resistance – Annex D


- 66 -

Characteristic Testing method Observations the design of pavements derived from 4-point fatigue

resistance – Annex D

Resistance to the effect of fuels (performance-related: for airport runways)

EN 12697-43, Resistance to fuels

This specification is applicable to asphalt mixes used on airfields

Resistance to deicing products (performance-related: for airport runways)

EN 12697-41, Resistance to deicing products

This specification is applicable to asphalt mixes used on airfields

a For asphalt mixes used on pavements and other traffic thoroughfares / roadways, with the exception of airport runways/taxiways.

b For asphalt mixes used solely on airport runways/taxiways.

2.7.2 Very thin asphalt concretes

These material specifications have been listed in Standard EN 13108-2 and are solely intended for the BBTM type (French acronym for very thin asphalt concrete).

Table 16 – Type of tests for BBTM (very thin layer asphalt concretes)


Binder content

(prescription)


and EN12697-39, Bitumen content by calcination

When type testing is performed with laboratory-made materials, the bitumen content considered is the quantity of bitumen incorporated into the mixture. On the other hand, when the testing is conducted with materials extracted from the plant, the binder content of the mix is determined by using one of these methods.

Particle size distribution

(prescription)

EN 12697-2, Particle size analysis

Method not employed in the case of type testing performed in the laboratory (see above).

Void percentage, including voids filled by binder and voids contained in the granular skeleton, void content Vmax ≤ 7%

(prescription)

EN 12697-8, Determination of specimen void percentage Apply EN 12697-6 (bulk density), Method B, dry saturated surface Apply EN 12697-5 (maximum density - MVR), Method A in water

Specifications on the void percentage pertain specifically to measurements conducted on test specimens within the scope of a type testing procedure.

For example, the void percentage of impact-compacted "Marshall" specimens must be determined in this manner.

Void percentage, including voids filled by binder and voids contained in the granular skeleton, void content 7 < Vmax < 10%

(prescription)

EN 12697-8, Determination of specimen void percentage Apply EN 12697-6 (bulk density), Method C, paraffin-sealed Apply EN 12697-5 (maximum bulk density - MVR), Method A

See above.


- 67 -

Characteristic Testing method Observations in water

Void percentage, including voids filled by binder and voids contained in the granular skeleton, void content Vmax ≥ 10%

(prescription)

EN 12697-8, Determination of specimen void percentage Apply EN 12697-6 (apparent bulk density), Method D by dimensions Apply EN 12697-5 (maximum density - MVR), Method A in water

See above.

Void percentages by Gyratory Compaction

(prescription)




EN 12697-12, Sensitivity to water

Method B (compression test) shall be used in France, even the result is noted ITSR.


EN 12697-16, Method A

Mechanical stability -

OPTIONAL

EN 12697-22, Large model, in air at a specified temperature

This reference corresponds to the LPC device and set-up.

This characteristic has not been listed for CE Marking, but does appear in the product standard, and can thus be used as a specification.

Resistance to the effect of fuels (performance-related)

EN 12697-43

Resistance to deicing products (performance-related

EN 12697-41 Resistance to deicing products

2.7.3 Soft asphalt concretes

These are listed in Standard EN 13108-3.

Table 17 – Type of tests for soft asphalt concretes


Binder content

(prescription)



cf. comments in table 15.


(prescription)

EN 12697-2 Particle size analysis



- 68 -


Void percentage

(prescription)

EN 12697-8, Determination of specimen void percentage

Apply EN 12697-6 (bulk density), Method B, dry saturated surface


2.7.4 Hot Rolled Asphalt These specifications are listed in Standard EN 13108-4.

Table 18 – Type of tests for Hot Rolled Asphalt


Binder content

(prescription)





(prescription)

EN 12697-2 Particle size analysis


Void percentage, including voids filled by binder and voids contained in the granular skeleton (prescription)


Apply EN 12697-6 (bulk density), Method A, dry condition



EN 12697-12, Water resistance


EN 12697-16

Resistance to permanent deformation (performance-related)

EN 12697-22, small model, Method A in air and Y cycles

Stiffness modulus (performance-related)

EN 12697-26

Resistance to the effect of fuels (performance-related: for airstrips)

EN 12697-43

Resistance to deicing products (performance-related: for airstrips)

EN 12697-41


- 69 -

2.7.5 Stone Mastic Asphalt These specifications are listed in Standard EN 13108-5.

Table 19 – Type of tests for the Stone Mastic Asphalt material Characteristic Testing method Observations

Binder content

(prescription)





(prescription)



Void percentage, including voids filled by binder

(prescription)

EN 12697-8

Apply EN 12697-6 (bulk density), Method B, dry saturated surface

Apply EN 12697-5 (maximum density), Method A in water

Void percentages of Gyratory Compactor specimens

(prescription)



Binder drainage (performance-related)

EN 12697-18, Drainage test


EN 12697-12, Water resistance Indirect tensile method or method B using compression.


EN 12697-16

Resistance to permanent deformation (performance related)

For Stone Mastic Asphalt mixes designed with axle loads < 13 T

EN 12697-22, small model, in air at a specified temperature


For Stone Mastic Asphalt mixes designed with axle loads ≥ 13 T

EN 12697-22, large model, in air at a specified temperature

This reference corresponds to the LPC device and set-up.


EN 12697-43


EN 12697-41


- 70 -

Figure 19: Small-scale rutting tester model operating in air

2.7.6 Porous Asphalt

These specifications are listed in Standard EN 13108-7 and encompass BBDr (French acronym Bétons Bitumineux Drainants for porous asphalts).

Table 20 – Type of tests for the porous asphalt


Binder content

(prescription)





(prescription)



Void percentage

(prescription)


Apply EN 12697-6 (bulk density), Method D by dimensions

Apply EN 12697-5 (maximum density - MVR), Method A in water

Void percentages by Gyratory compaction

(prescription)




- 71 -


Permeability (performance-related)

EN 12697-19, Laboratory-based permeability test


EN 12697-12, Water resistance Method B(compression test) shall be used in France, even the result is expressed as ITSR.

Bitumen - aggregate affinity (performance-related: for airport runways/taxiways)

EN 12697-11, Binder - aggregate affinity, Part C: Static method

Binder drainage (performance-related)

EN 12697-18, Drainage test

Mass loss (performance-related)

EN 12697-17, Abrasion test The "Cantabre" test (deemed not pertinent for specifications purposes).


EN 12697-43


EN 12697-41

LPC Bituminous Mixtures Design Guide - Mix Design Procedure -

- 73 -

3 MIX DESIGN PROCEDURE The procedure employed to design material mixes has not been codified. The focus herein relies upon meeting the requirements identified from the type testing stage described in Part 2. The mix design process begins by selecting the set of components: aggregates, fines, binder, and additives. In some instances, these components may be imposed by the contracting party. Knowing the characteristics of mix constituents is critical as of the initial mix design phase and will also prove useful for all subsequent mix adjustments/refinements should test results not comply with specifications. The procedure entails adjusting the mix composition using the Gyratory Compactor test, complemented afterwards by the set of tests stipulated for the particular testing level in correspondence with the chosen design. This procedure has been laid out in the diagram below. The sections that follow will detail these various stages in association with the recommendations issued by practitioners.

3.1 Component selection

3.1.1 Aggregates

3.1.1.1 Fines and added fillers According EN 13043, fines and added fillers are characterized after a dry sieving with a 0,125 mm sieve by a voids of dry compaction test (Rigden Void Index), by a ∆TR&B test and by the identification of the methylene blue value MBF.

Selection of components

Gyratory Compactor test

Design of the prototype mix composition

Type testing

yes

no

Change in component(s)

Adjustments of the particle grading curve


- 74 -

Choice The added filler is not, in all instances, definitively chosen at the same time as establishing the mix design. In some regions, the added filler stems from just a single source, thereby simplifying the procedure. While several different plants may able to accommodate supply needs, the mix designer must be provided an identified set of samples and then select a "feasible" supplier. The mix composition can also be produced using the same kind of "average" filler under all conditions.

Type Fine limestone aggregate tends to be predominant as a choice of added filler, yet other filler types may be used as a replacement or complement by virtue of their specific properties. For instance, cement may be used as a replacement for the limestone filler, yet it would be preferable to limit its concentration to just 3% or 4%. Beyond this threshold, cement hydration in the mixture can exert influence on the I/C ratio (Duriez test corresponding to method B of EN 12697-12); moreover, cracking problems may arise as well. Calcium hydroxide (quicklime) is introduced into the mix in order to prevent the so-called "soup" phenomenon from appearing; such a phenomenon can be observed during mixing as water gets held by porous aggregates. It would be worthwhile to use calcium hydroxide (quicklime) for improving the level of water resistance; in addition, its concentration would need to be limited to 1% (due to the risk of swelling), and precautions to avoid inhalation would need to be taken. The active filler is a mix of limestone fines and calcium oxide (slaked lime), which has the same use properties as quicklime. Slaked lime gets added as a drainage retardant on porous asphalts (PA-BBDr). Its concentration of between 10% and 25% lime, as compared to limestone filler, allows obtaining a mastic whose ∆TR&B increases by 4°C to 7°C with respect to the ∆TR&B value of the base filler. Slate is introduced for its extremely high stiffening power (i.e. a ∆TR&B of more than 38°C, a methylene blue value of around 0,3 g / 100 g, a Rigden Voids Index in the neighborhood of 45%, and an absorbent power lying near 26). Should fly ash from coal-fired power plants be used, it would be advised to monitor mass density values as these may fluctuate. The additives are composed of hollow spheres and their absorbing power varies widely. Similarly for cement fillers, which are industrial by-products, the methylene blue value needs to be verified.

The effect of the presence of ultra-fine particles on the properties of mastic and asphalt mixes is not well known. An experiment focusing on a specially-prepared limestone filler with an increasing proportion of ultra-fine particles did not conclude the presence of any significant effect on ∆TR&B.


- 75 -

Mastic The combination of bitumen and filler within a hydrocarbon mix gives rise to a mastic whose properties will influence a portion of mix characteristics. Said properties are basically evaluated via the ∆TR&B value. High ∆TR&B values tend to enhance rutting resistance, and excessive values of ∆TR&B could constitute a cracking risk.

Voids in dry compacted filler (Rigden Void Index) v: High Rigden Void Index values generally imply a rise in binder content (also in richness modulus), so as to yield a volume of free bitumen equivalent to that obtained in a readily-available material.

Harmfulness

Example – Effect of clay content on mix characteristics:

The inclusion of clay into the fines of a crushed aggregate for the purpose of experimentally increasing the methylene blue value (bentonite, kaolinite, illite) has induced the following effects on the characteristics of a mix (AC-BBSG, AC-GB):

– Rise in the percentage of Gyratory Compactor voids (+ 2 for VB = 2g/100g) – Decrease in rutting depth (2,3 mm for VB = 4g/100g) – No visible effect on the I/C (r/R Duriez test) ratio (at 7, 14 or 28 days) – Significant stripping of mortar even after 7 days, as I/C drops 0,10 to 0,25 points

Keep in mind that the studied mix was artificial. Transposing results to commonly-used mixes is not always straightforward.

[LPC Report No. 14]

3.1.1.2 Fine aggregate The criteria relevant to sands or fine aggregate that serve to influence asphalt mixtures are as follows:

Particle size distribution (grading) curve Special consideration needs to be given to hollow curves with a very small fines content that hinders mix compactability.

Angularity The angularity of fine aggregate exerts a major impact on the mixture's rutting resistance. The characteristics of how crushed aggregates are produced even when derived from solid rocks can heavily influence mix characteristics. Aggregates could display chipped edges due to processes involving recycling, grinding, etc. Their internal friction thus drops considerably and might alter mix stability. This problem could ultimately be revealed through the fine aggregate flow coefficient of the test described in EN 933-6. A visual inspection using binoculars remains the most effective means of detection for a well-trained eye.


- 76 -

Example – Effect of angularity (with solid rock):

In two AC14-BBSG samples containing approximately 30% fine aggregate of the same origin, yet from different production facilities (these fine aggregates differ by 6 seconds when submitted to the flow test), it was found that:

Ground solid rock => wheel tracking test result: 8% after only 1000 cycles

Crushed solid rock => wheel tracking test result: 5% after 30000 cycles

[Corté et al, 1994]

Whenever the percentage of voids for a mix becomes excessive, the inclusion of a small proportion of totally rounded fine aggregate serves to reduce this percentage. The following limitations must nonetheless be noted: the use of fine totally rounded aggregate on a road pavement is strongly discouraged, while application of this type of fine aggregate must be confined to road mixes submitted to very limited risks of rutting. The suggested concentration is held to 10% for asphalt concretes for surface courses and must not exceed 20% for base courses. The effect of low angularity may, in some instances, be compensated by using a "hard" grade binder when the mix is being applied as a base course or foundation. It is still advised, in all cases, however to ensure stability of the granular skeleton.

Resistance to fragmentation or to wear (Hardness) Whenever physical characteristics differ among the mix's various granular fractions, the softest aggregate may undergo attrition. One illustration would be the frequent case of finding a soft sand along with harder coarser aggregates. Some distinctions might be limited to just a single category. The converse (i.e. harder sand with softer coarse aggregates) could not be accepted for application as a wearing course. Should the origin of the fines fraction be different from that of the coarse aggregates, it would be necessary to submit the fines to a friability test, Vss = 40 for a all-in aggregate 0/4, and Vss = 45 for a fine aggregate 0/2.

3.1.1.3 Coarse aggregates The set of criteria relative to coarse aggregates that serve to influence bituminous road-building materials are as follows:

Type of rock

Frictional materials: Materials are said to be "frictional" when the percentages of voids observed on Duriez test specimens (Method B of EN 12697-12 is derived from Duriez test) lie close to values recorded in situ, whereas the Gyratory Compactor indicates a lack of workability (as translated by an excess in voids on the order of 4-5%) for the specified number of gyrations. This phenomenon has been observed with certain basalts, granites and gneiss.

Workable materials: Materials are said to be workable if, despite exhibiting high angularity, their standard particle size distribution leads to a small percentage of voids.


- 77 -

Porous materials: These materials absorb, through their inherent porosity, a portion of the bitumen and engender mixing difficulties. This phenomenon has been remarked with basalts, slag and dolomitic limestone. The level of absorption can be measured by means of lacquering the aggregates with bitumen and then recording the maximum density (MVR) value both before and after lacquering. Evolutive materials: This category of materials displays alterations in characteristics over time and, for example, would comprise steel slag and LD dross.

Example – The case of dross from the Fos-sur-Mer "LD" steel mill:

These aggregates are of artificial origin. They have been used:

– for several years in the form of 0/4 all-in aggregate, to adjust angularity on overly-workable mix designs (AC-BBSG, AC-BBM, BBTM); and

– much more recently in the form of coarse aggregates, as an alternative to aggregates with high CPA values[ Former test for PSV : PSV= 100CPA + 1,5] (0,5 to 0,6), which prove to be rare and expensive in the region around Fos-sur-Mer (south of France). Their mass density level is quite high (3,1 to 3,7 g/cm3).

These materials are steelmaking by-products contained in "LD" converters, which serve to transform hematite pig iron into steel. Prior to application, they undergo the following treatments: 1. Metal removal; 2. Crushing to 0/2 mm; 3. Bulk storage for a period ≥ 1 year in order to slake nearly all of the quicklime contents; 4. Screening.

This procedure is presumed to cancel the effects produced by aggregate swelling when hydrating the lime contained in the original materials. The literature on this topic and procedure is vast.

[CTPL publication, CRR Study Series]

Shape Aggregates shaped too much like cubes could lead to excessive workability. The flakiness Index FI should, as a preferred value, lie between 10 and 15.

Example – "Shape" effect of a coarse aggregate on mix behavior:

Effect on void content: AC14- GB containing 4% (out) bitumen (Solid rock N - crushed)

Flakiness 2/14 fraction

% voids after 100 gyrations AC14-GB

3,7 5,8

9,5 8,9


- 78 -

Effect on wheel tracking: AC14-BBSG containing 5,7% (out) bitumen, Solid rock C - ground – Solid rock N - crushed

Flakiness 2/14 fraction

Rut depth (in mm) after 1000 cycles

AC-BBSG

Rut depth (in mm) after 3000 cycles

AC-BBSG

3,7 15 Deformation too high to be measured

9,5 9 18

Angularity This characteristic influences mix stability and affects the material's surface characteristics. The "type of aggregate" parameter could produce an effect 3 to 4 times greater than that of the "bitumen grade" parameter with respect to rutting.

[AAPT 1988, v 57]

An additional 7°C over the bitumen R&Β would be needed in order to compensate for "poor angularity".

Aggregate processing mode The type of crusher used and its mode of operations affect, for a given crushing ratio, both the shape and aspect of aggregate edges. Mix performance (i.e. wheel tracking and compacity), as a consequence, also gets affected.

Example – Effect of crushing mode on a alluvial AC10-BBSG from the Durance:

(1) Tertiary Gyratory crusher (2) Vertical anvil axis (3) Vertical pebble box axis

Crushing mode

Angularity- fine

aggregate (flow time)

Angularity-coarse

aggregate (flow time)

Crushing ratio Rc

Gyratory Compactor

60 gyrationsVoid %

Rutting at 3000 cycles - % rut depth

Rutting - after30000 cycles

Gyratory crusher 39 124 4 9,8 3,2 5,7

Anvil axis 37 122 4 9,7 3,2 5,4

Pebble box axis 33 106 4 6,7 10,8 Deformation too

strong to be measured

[Mines and quarries, October 1996, Volume 78]


- 79 -

Other characteristics A high coefficient of dilatation weakens the mix at low temperature… [RGRA 753, p. 52]

To shade the material or to complement the use of both light and colored binders in an effort to obtain a more distinct hue, specially-colored aggregates may be chosen (these choices would include the fine aggregate component). Light-colored aggregates are sometimes employed to: reduce the "black body" effect of mixes, lessen pavement heating, and thereby lower the risk of rutting. Such aggregates can also be used as a surface layer in tunnels to limit the need for additional artificial lighting.

As an illustration, the introduction of quartzite (white) instead of the more conventional diorite (gray) has resulted in an observed drop of between 2°C and 5°C (between normal and exceptional summertime conditions) within the first centimeter of pavement. The associated use of a light-colored binder gives rise to a further 3°C decrease.

[Light-colored asphalt concretes on the Paris ring road, RGRA 735, p. 57, December 1995]

3.1.2 Binder

3.1.2.1 Origin The origin of the binder used on a road-building site is not always known when designing the material mix. To conduct the Gyratory Compactor test, since bitumen origin does not affect the result, it is possible to implement the same grade bitumen as that specified for the works. In order to characterize a mix based on the water-sensitivity test by compression, as well as on the wheel tracking test and a determination of the stiffness modulus or fatigue resistance, the origin of the bitumen used will influence ultimate test results. Should the specified bitumen be unavailable, it would be appropriate to use either a "feasible" bitumen or a "standard" bitumen very familiar to the mix designer. Once the actual "project" bitumen is effectively known, an estimation of the alteration introduced needs to be carried out.

3.1.2.2 Type of bitumen The choice of bitumen must enhance the attainment of required product performance. Some performance measures have been included in the type testing protocol conducted on the mixtures (i.e. water resistance, rutting resistance, stiffness modulus, fatigue resistance), yet others are not directly expressed via test results (material aging, oxidation, "top-down" cracking, etc.). A series of empirical specifications based on more conventional tests can then be developed.

Paving grade bitumen To better prevent against cracking risks under severe traffic and climatic loading conditions, it would be advised to select the softest grade compatible with rutting resistance-based requirements. For purposes of illustration, the following tendencies may be considered (from the French Standard Mix Application Guide).


- 80 -

Table 21– Suggested bitumen grade by mix type

Type of mix Loading Suggested grade

Mixes for wearing courses AC-BBSG, AC-BBM, BBTM, PA-BBDr and AC-

BBA materials Heavy

35/50 50/70 (airfield pavement NS3)

20/30 may be used for class 3 of AC-BBSG and AC-BBME

Mixes for wearing courses AC-BBSG, AC-BBM, BBTM and AC-BBA materials Light

50/70 70/100 at higher altitudes, and in continental zones and airfield zones submitted to lighter

loads (NS1, NS2)

Mixes for base courses / foundation layers 35/50

Lower thermal susceptibility bitumen This category of pure bitumen has been specially produced and features a penetration at 25°C that corresponds with the standardized grade (e.g. 35/50 or 50/70), yet whose ring and ball temperature typically exceeds the standardized limit for the corresponding grade. The Fraass temperature is also lower than that of similarly-graded pure bitumen samples (≤ -15°C). They are used in particular for improving the rutting resistance properties of materials.

"Hard" bitumen This category of pure bitumen is obtained by means of a direct refining process and displays a penetration of less than 25 1/10 mm. Two categories 10/20 and 15/25 are defined according to EN 13924. The French recommendation for the ring and ball temperature is between 60°C and 76°C for 10/20 and between 55°C and 71°C for 15/25. The Fraass temperature (out of the French recommendation) lies near 0°C (from +3°C to -8°C). The mixing temperature exceeds by approximately 20°C that associated with conventional bitumen mixes. The primary application of this type of binder relates to the EME high-modulus materials. The hardness of this type of bitumen can induce brittleness at low temperature; it would thus be advised to use such mixes along with thermal protection when employed in harsher climates.

Modified bitumen Modified bitumen materials are bituminous binders whose properties have been altered by the introduction of a chemical agent that, added to the basic bitumen, acts to modify both the chemical structure and physical and mechanical properties. In all cases for such materials, precautions must be taken to avoid the risk of instability, creaming and sensitivity to thermal loading history. Section 1.4.2.2 provides a description of the main types of modified bitumen. The shortfall in performance-based specifications on these materials necessitates the systematic assurance that use of such a binder serves to obtain the desired mix performance, hence the quality of modified bitumen and, consequently, the resultant mix properties are not solely dependent upon polymer content. Moreover, it should be pointed out that for modified binders, the ring and ball temperature does not


- 81 -

constitute a relevant criterion when it comes to evaluating asphalt mix behavior at high service temperatures. Modified binders are basically used in surface layers in both BBTM and BBDr materials. The ultimate application is what distinguishes the various modified binder families for individual supplier-specific uses. Some products have been the topic of Technical Guidelines, published by the SETRA Highway Engineering Agency, which sets forth use conditions and performance levels obtained on reference jobsites.

Pigmentable bitumen This category of bitumen and the resultant mixes show greater susceptibility to temperature than materials containing "normal" bitumen. Such components are reserved for more urban type applications or one-off uses intended to render lane indications more easily legible.

Synthetic binders Synthetic binders display a number of behavioral differences in comparison with conventional bitumen, namely: - their susceptibility to temperature may be very different from that of a similarly-

graded standardized bitumen; and - their mixing temperature must be indicated by the supplier; it may vary on the

order of 15°C with respect to that of a pure bitumen of the same consistency. Their range of application overlaps with that of pigmentable bitumen.

Bituminous binders with mineral loads These ready-to-use binders are obtained from plant mixtures of pure bitumen and mineral loads, e.g. lime. Binder content differs from bitumen content, and the objective herein tends to focus on "stiffening" the mix.

Agrochemical binders These binders are made from vegetal matter without any petrochemical byproduct. The result is transparent and may be colored. Its applicability is currently being assessed.

3.1.3 Additives Section 1.4.3 provides a comprehensive description of the primary additives.

3.1.3.1 Effect of type of additive

Polyethylene This additive is intended to improve the level of rutting resistance and increase the stiffness modulus; it partially associates with the bitumen. The concentration level typically lies between 0,4% and 1%, with respect to aggregate quantity. It should be remarked that polyethylene at the melting point plays the same role as bitumen. A standard concentration of polyethylene thus serves to decrease the binder concentration of the reference material by some 0,15%.


- 82 -

Similarly, the increase in fatigue characteristics observed when adding polyethylene is solely correlated with the corresponding rise in binder quantity.

Example – Effect of polyethylene concentration (from cable waste) on rutting resistance Test conducted on a AC14-BBSG mix containing 32% finely-crushed aggregate,

initially leading to 15% rutting after 3000 cycles NOTE: The mix's bitumen content has been lowered by 0,15%, in comparison with the reference mix, to account for the addition of polyethylene.

Polyethylene concentration (%, with respect to the dry aggregate)

Rut depth after 30,000 cycles (mm)

0,5 9

0,8 5

1,1 4

[Experiment conducted on aggressive loads, No. 3, Fatigue Carrousel]

Polymers These additives are intended to decrease the effect of binder susceptibility.

Fine rubber crumb fraction and 2/6 rubber aggregates These additives contribute to improved cracking resistance, in addition to damping the impact from tires.

New and recycling fibers Incorporated at the time of mixing, these fibers act like a bitumen reservoir once in the mix; they can either increase bitumen content, without raising the risk of rutting (added to BBTM and SMA mixtures), or avoid drainage problems (for PA-BBDr). Depending on the type of fibers added, the mode of laboratory preparation must be adapted while continuing to respect the mode selected for including this additive in an industrial setting. The fibers may be mixed to the binder either as a preliminary step or introduced into the dry mix or perhaps after incorporation of the bitumen.

3.1.3.2 Natural bitumen and asphalts This category of additives is to be used as a substitution for directly-distilled bitumen in order to obtain a stiffer mix by means of a combined binder hardness and added filler effect.

3.1.3.3 Pigments The concentration of pigments depends on the desired effect, aggregate color and type of bitumen. For a light-colored synthetic binder, this concentration lies on the order of 0,5% and can rise as high as 2%. With a pigmentable bitumen, the concentrations are higher, reaching the neighborhood of 2,5% to 4%. This case is generally limited to use of the color red. It would be necessary to consider the pigment concentration like fines within the mix.


- 83 -

The product is then incorporated into the dry mixture prior to adding the bitumen. The mix's mechanical characteristics, especially water resistance and if applicable rutting resistance, are to be verified. Oxides can actually influence binder-aggregate adhesion and the choice of associated bitumen (either pigmentable or synthetic) can influence rutting resistance.

3.2 Relationships between binder properties and mix properties

3.2.1 Penetrability and ring and ball temperature

The test of penetrability at 25°C is correlated with stiffness of the mix at service temperatures. The stiffness modulus of bitumen may be deduced from both the penetration test at 25°C and the ring and ball temperature, by means of the Van der Poel abacus (see Fig. 29). Ring and ball temperature is an effective indicator of the binder's contribution to rutting resistance. This criterion loses its relevance however for modified binders.

Example – Effect of ring and ball temperature

On 3 types of asphalt mixes, a 7°C rise in the ring and ball temperature of a bitumen allows increasing tenfold the number of cycles leading to a given rutting depth.

3.2.2 The SHRP criteria The Strategic Highway Research Program (SHRP) set up in the United States has sought to define the relationships between binder characteristics and mix characteristics. The tests conducted on binders have been aimed at ascertaining rheological aspects. The binder performance – mix performance relationships are the current focus of research efforts. A few of these relationships have already been published, yet their pertinence for French mixes still needs to be verified.

SHRP criteria and tests conducted on asphalt mixes

According to the SHRP, rutting resistance is effective if G*/sin δ > 1 kPa (for new binder) and > 2,2 kPa (for binder having undergone RTFOT). This relationship is not always verified with the LPC rutting tester. In contrast, the criterion G*/sin δ > 3.8 kPa leads to low rutting rates [RGRA 730]. The SHRP criterion relative to fatigue resistance is expressed as: G*sin δ < 5 kPa (RTFOT + PAV). A verification on AC10-BBSG mixes serves to confirm this trend, although the correlation is not very strong. Sin δ does not contribute any more than G*, and ε6 is not directly correlated. The slope of the fatigue line enters into consideration. Cold resistance: The SHRP criteria are: S(60) < 300 MPa and m > 0,3 (with the doubt over whether either of the two criteria is being met: a tensile deformation test at failure > 1% is thus conducted). The criteria selected in France are: temperature isomodulus I G*I = 300 MPa for a 1000 s loading time and slope m. Correlation with the theoretical brittleness temperature proves to be strong.


- 84 -

3.2.3 Origin of the bitumen

Both the origin and processing mode for bitumen materials may exert a significant influence on mix characteristics. Some test results depend heavily on these parameters – a few examples have been provided below:

ε 6 and the origin of bitumen The fatigue resistance ε6 measured by the deformation test required on mix specimens with bitumen featuring the same characteristics, yet of different origins, varies between 88 µdef and 150 µdef, all other parameters being held the same.

[Statistical study of the effect of asphalt mix composition on material fatigue behavior,F. Moutier, BL, No. 172, p. 40]

Relationships between the stiffness moduli for both binder and mix

On any given mix, relationships between the stiffness moduli of both the binder and mix (containing modified binders) of the type lg (E*) = 0,71 *lg (G*) + 3,04 have been established.

[RGRA 739, p. 22]


- 85 -

3.3 Initial composition by type of material Depending on the set of requirements and available materials, the mix designer determines a composition that corresponds to an initial targeted particle size distribution curve, as well as a bitumen content and, ultimately, the proportions of admixtures. This initial composition is established in accordance with knowledge derived from previously-studied mixtures, initial mix design curves, mix family ranges and binder content (or richness modulus) values while incorporating the effects of additives and the absorbing power of fillers on binder content. The initial compositions (particle size distribution curve, binder content) by type of material will be discussed in the following sections and listed in the summary table presented in Appendix E and in Appendix F.

3.3.1 Asphalt Concretes for base course – Grave-Bitume AC-GB and High Modulus AC-EME

Figure 20: Cross-section of a Grave-Bitume AC-GB mix

3.3.1.1 Remarks concerning mix components

Aggregates For some of the fines from basalt aggregates, crushed slag and highly-acidic granite, either active fillers or hydrated lime needs to be used. Most hard limestone sand generates a high level of workability: the percent passing the 2-mm sieve on the AC-GB particle size distribution curves must be reduced to approximately 30% or else the wheel tracking test would have to be considered. Some of the natural fillers from fine aggregate are noxious despite being able to satisfy cleanliness specifications. As an example, dolomite leads to water resistance problems, as do certain forms of tuff, even though the methylene blue value seems to be adequate.


- 86 -

The amphibolites-gneiss and a number of porphyries yield low I/C (r/R) ratios (whereas amphibolite-diorite ratios are very strong). For the AC-EME and AC-GB mixes, it is possible to correct for the angularity effect through bitumen hardness and concentration. The durability however has not been established. The hard limestone materials make it possible to obtain high readings of compacity, even with moderate binder content. This high compacity, coupled with relatively low binder content, has resulted in increased stiffness modulus values. For some granite materials, water resistance still needs to be verified.

Bitumen and additives For Grave-Bitume AC-GB: As a general rule, 35/50-grade pure bitumen is used. Grade 50/70 may also be employed for convenience sake, for example at stationary mixing plants. In mountainous regions or in the case of low-level loadings (as intended by the Mix Standards Application Guide), implementation of the 50/70 grade is indeed possible. On the other hand, a grade above 70/100 must not be used. Within specifically-designated zones (traffic > T0 [more than 750 lorries per day], channeled traffic flows, slow speeds < 40km/h, a ramp inclined at over 5%), it is advised to select the 20/30 grade or a special bitumen with low thermal susceptibility, should the desired result not be reached with a 35/50 grade. Adding polyethylene to bitumen-aggregate mixes does not seem to be beneficial (rarely justifiable given current mix designs).

For High Modulus Asphalt concrete mixtures AC-EME: These are most often produced using an hard-grade bitumen as stipulated by EN 13924 and in conjunction with 10/20 or 15/25 grades. The recommended characteristics for this type of binder are as follows: - standard penetration: 10 to 25 1/10 mm; and - ring and ball temperature: between 62°C and 72°C, or even 80°C. The 20/30 grade may be acceptable along with other grades (35/50 in particular), combined with admixtures (e.g. natural bitumen) or polyethylene. Polymer-modified bitumen serves to increase the value of ε6. The addition of 0,7% polyethylene within a 35/50-based mix offers a potential gain of approximately 20% in stiffness modulus. The presence of fibers exert little influence on modulus values.

3.3.1.2 Composition of the granular mix

Particle size distribution curves tend to be continuous. It is possible to introduce discontinuities into the [4/6] or [6/10] distribution curve. Discontinuities typically have little impact on material characteristics. Should the curve show coarse granularity (percent passing 2-mm sieve on the order of 28%), it would be necessary to raise the filler content to about 7,7%. Table 22 presents the initial grading curves for AC20 or AC14 Grave-Bitume AC-GB and High Modulus Asphalt concrete AC-EME mixes. The French foreword of EN


- 87 -

13108-1 also calls for the possibility of producing a AC10-EME, whose corresponding initial grading curve has been listed in Table 23.

Table 22 – Initial AC20 or AC14 Grave-Bitume AC-GB and High Modulus Asphalt Concrete AC-EME grading curve

D = 20 mm or 14 mm Typical range of variations Sieve passing,

in mm Minimum Target value Maximum

6,3 45 (50 for 0/14) 53 65(70 for 0/14)

4 40 47 60

2 25 33 38

0,063 5.4 6.7 7.7

Table 23 – Initial AC10-EME grading curve

D = 10 mm Typical range of variations Sieve passing,

in mm Minimum Target value Maximum

6,3 45 55 65

4 52

2 28 33 38

0,063 6,3 6,7 7,2

3.3.1.3 Bitumen content

The bitumen content at the beginning of this study is taken from Table 24 or calculated from the specific surface area of the mix, the maximum density (MVR) value and the minimum richness modulus associated with the standard. For information, the previous “external binder content” is also mentioned in table 24


- 88 -

Table 24 – Typical initial binder content of AC-GB and AC-EME (richness modulus)

AC-GB2 AC-GB3 AC-GB4 AC-EME1 AC-EME2

D in mm 14 20 14 20 14 20 10 or 14 20 10 or

14 20

Binder content Bmin for ρ = 2,65 g/cm3

4,0 4,0 4,5 4,4 4,7 4,6 4,0 4,0 5,4 5,3

Binder content Bmin for ρ = 2,75 g/cm3

3,9 3,9 4,3 4,2 4,5 4,4 3,9 3,9 5,2 5,1

Typical target of richness modulus K 2,5 2,8 2,9 2,5 3,4

External binder content TLext for ρ = 2,75 g/cm3

4,0 4,0 4,5 4,4 4,7 4,6 4,0 4,0 5,5 5,4

3.3.1.4 Experimental results A sample of experimental results capable of influencing the mix designer is given in the following study:


- 89 -

Influence from type of aggregate and rheology of hard bitumen on the properties of hot asphalt mixtures used as a pavement base course and foundation layer

P. Bauer - S. Glita - P. Chaverot - J.M. Michou - P. Perdereau - Y. Vincent Eurasphalt & Eurobitume 1996. 4.050

Bitumen characteristics

Units Mixelf 10/20 15/25

Before RTFOT

After RTFOT

Before RTFOT

After RTFOT

Before RTFOT

After RTFOT

Penetrability at 25°C 1/10 mm 15 10 13 10 21 13

Ring and ball temperature °C 68 73,5 69 75 62 72

Constant richness modulus: 3,65; AC14-EME - type 2; particle size distribution curve ~ constant Aggregate characteristics: 4 origins: D; Q; C; SC (SC is an alluvial material)

Results from Gyratory Compactor testing

Aggregate D Aggregate Q Aggregate C Aggregate SC Slope K 3,65 3,44 4,12 3,27

Voids calculated for 1 gyration % V1

22 21 23,9 19,4

Voids at 100 gyrations % V100

5 5,1 4,8 4,2

Results from wheel tracking tests

60°C, 30,000 cycles: rutting depth less than 5 mm, regardless of binder and aggregate, except for aggregate SC (6 to 8 mm).

Stiffness modulus test in direct tension

10°C, 0.02 sec: The stiffness modulus exceeds 20000 MPa.

Aggregate origin induces a 20% variation (Mixelf bitumen). (increasing trend C -> SC -> Q ->D)

Bitumen origin leads to a 10% deviation for aggregate C (15/25 -> {10/20 & Mixelf}) and an 18% deviation for aggregate D (15/25 -> {10/20 & Mixelf}).

Complex modulus test

15°C, 10 Hz Aggregate origin produces an 18% deviation (Mixelf bitumen) (C=SC=Q->D)

Fatigue test No "aggregate" effect


- 90 -

3.3.2 Thick layer mixtures for surface or binder course – AC-BBSG, AC-BBS, AC-BBME

Figure 21: Cross-section of a AC-BBSG (Asphalt Concrete Béton Bitumineux Semi-

Grenu)

Figure 22: Surface appearance of a AC-BBSG(Asphalt Concrete Béton Bitumineux Semi-

Grenu)


Aggregates For some fine aggregates from basalt aggregates, crushed slag and certain highly-acidic granite materials, either mixed fillers or lime must be employed. Most hard limestone fine aggregates provide for a good level of workability: the percent passing 2 mm on the AC-BBSG or AC-BBME grading curves must be reduced to approximately 30% (or even less). Some natural fillers from fine aggregate are noxious even if harmfulness specifications have been satisfied. For example, dolomite (cleanliness of sands with an sand equivalent rating ≥ 70, the blue value (stain) ≥ 2 g (i.e. approximately MBF ≥ 2,000 g/kg)) leads to water resistance problems, as do certain forms of tuff, despite a blue value that lies on the order of 0,8 g. The amphibolites-gneiss yield poor I/C (r/R) ratios for the watersensitivity, while the amphibolite-diorite results are quite strong. The brittleness of the fine aggregate would provide an indicator of the contribution from fines towards rutting resistance. The angularity of fine aggregate affects mix stability. It is advised to be cautious of ground fine aggregate and fine aggregate (or all-in aggregate) output from crushers with a revolving floorplate. The shape of mineral particles could make the mixture more sensitive to rutting. - Granite: water resistance requires verification. - Basalt: binder content to be adapted to better account for eventual absorption. - Limestone: coarse limestone aggregates are not permitted for use in wearing

courses (on the national highway network).


- 91 -

- Angularity and shape: the angularity of coarse gravel influences texture, as does the coarse aggregate shape. An overly regular shape would be deleterious and is to be avoided.

The flakiness index FI must preferably lie between 10 and 15. For a AC14-BBSG mixture: A percent passing of 34% with 2 mm sieve conducted at a texture in situ at ATD = 0,4 mm. A percent passing of 28% with 2 mm sieve conducted at a texture in situ at ATD = 0,7 mm.

Binders and additives For a AC-BBSG mixture, the following is used: - 35/50 grade pure bitumen in the case of heavy loadings and altitudes lower than

500 m, or a 50/70 grade in more typical cases and eventually a 70/100 grade in mountainous zones with harsh climate (categories advised in the Standards Application Guide); and

- special bitumen with low thermal susceptibility, or a polymer-modified bitumen for specific loading conditions (ramps, intersections, bus lanes). Adding 0,5% to 0,8% polyethylene serves to improve rutting resistance (in particular for the purpose of obtaining a Category 3).

A AC-BBS (“soft flexible asphalt concrete for low trafficked pavements) mixture is to include: - 50/70 or 70/100 paving grade bitumen. For a AC-BBME mix, the following are used: => 35/50 grade bitumen, potentially combined with additives; => "hard" bitumen, but not from 10/20 category, whether modified by polymers or not.

3.3.2.2 Composition of the granular mix The initial particle size distribution curves for AC-BBSG, AC- and AC-BBME are given in Table 25. It should be pointed out that the AC-BBS mix comprises a wider range of application thicknesses (4 to 12 cm) than both AC-BBSG and AC-BBME. This difference could lead to targeting a higher percent passing value at 2-mm sieve (capable of reaching 40%).

Table 25 – Initial AC-BBSG, AC-BBS and AC-BBME grading curve

Percent passing sieve, in mm

Typical values D = 14 mm

Typical values D = 10 mm

Minimum Target value Maximum Minimum Target

value Maximum

10 78 97

6,3 47 52 58 45 57 68

4 47 52

2 25 31 35 27 34 39

0,063 6,3 6,8 7,2 6,3 6,7 7,2


- 92 -


Bitumen content at the beginning of this study is taken from Table 26 using the maximum aggregate density equal to 2,65 g/cm3or to 2,75 g/cm3, or calculated from the specific surface area of the mix, the maximum density (MVR) and the richness modulus as done in the former French standard. The former external binder content with a maximum density of 2,75 g/cm3, characteristic of an average French value, is also mentioned. To complement this input, Appendix C provides the correspondence table between external and internal binder content, calculated for an identical mass density of 2,65 g/cm3.

Table 26 – Initial BBSG, BBME and BBS richness modulus and binder content

AC10-BBSG, AC10-BBME

AC14-BBSG, AC14-BBME

AC10-BBS1

AC10-BBS2

AC14-BBS3

AC14-BBS4

Binder content Bmin for

ρ = 2,65 g/cm3 5,5 5,2 5,3 5,7 5,2 5,0

Binder content Bmin for

ρ = 2,75 g/cm3 5,3 5,0 5,1 5,5 5,0 4,8

Typical target of richness modulus K

3,5 3,3 3,4 3,7 3,4 3,1

External binder content TLext for ρ = 2,75 g/cm3

5,6 5,3 5,4 5,8 5,3 5,0

3.3.3 Porous asphalt mixes – PA-BBDr

Figure 23: Cross-section of a Porous Asphalt (PA-BBDr)

Figure 24: Surface appearance of a Porous Asphalt (PA-BBDr)


- 93 -


Aggregates The aggregates consist for the most part of solid rock. Should granite be used, the level of water resistance needs to be verified. The Los Angeles value becomes very important in avoiding compaction-induced fragmentation. Polish Stone Value, PSV, plays a key role in improving the skid resistance parameter. The flat coarser aggregates are also exposed to the effects of fragmentation. For each d/D fraction, controlling the tails of the d curve proves determinant to obtaining the desired percentage of voids. Some guidelines call for introducing 1% quicklime in order to incite greater adhesiveness. The use of slaked lime is intended to stiffen the mortar as a means of avoiding drainage.

Binders and additives The binder may be either a 50/70 or 35/50 grade pure bitumen or a polymer-modified bitumen. With the polymer-modified bitumen, it would be necessary to increase the concentration by 0,4%. The recommendations on extra binder concentration are not unanimous. Some research favors systematic reliance (at a rate of 0,3%). For the water-sensitivity test, the I/C (r/R) ratio is not always an accurate indicator (due to the risk of aggregate fragmentation during the compaction by compression of specimens as in a Duriez test). Additives are primarily intended to lower the risk of drainage. Fibers (cellulose, glass or rock) are introduced at a rate of 0,3%.


The initial PA-BBDr particle size distribution curves are specified in Table 27. The drainage capacity of the mix is affected by the percentage passing the 2-mm sieve.

Table 27 – Initial PA-BBDr grading curve

Sieve size

Porous Asphalt

(PA-BBDr)

D, in mm

Gap-graded fraction

6,3 mm (%)

10 mm (%)

2 mm (%)

0,063 mm(%)

0/10 2/6 13 13 ± 2 3,5 Category 1

0/6 2/4 10 10 to 13 3,5

0/10 2/6 8 8 ± 1 3,5 Category 2

6/10 2/4 5 5 ± 1 3,5


- 94 -


Bitumen content at the beginning of this study is taken from Table 28 using the maximum aggregate density equal to 2,65 g/cm3or to 2,75 g/cm3, or calculated from the specific surface area of the mix, the maximum density (MVR) and the richness modulus as done in the former French standard. The former external binder content with a maximum density of 2,75 g/cm3, characteristic of an average French value, is also mentioned. To complement this input, Appendix C provides the correspondence table between external and internal binder content, calculated for an identical mass density of 2,65 g/cm3.


- 95 -

Table 28 – Initial Porous Asphalt (PA-BBDr) binder content (Richness modulus)

Category 1

PA10-BBDr1 (%)

PA6-BBDr1 (%)

Binder content Bint for an aggregate mass density

ρ = 2,65 g/cm3

Paving grade bitumen: 4,4 to 4,8Fibers: 5,1 to 5,5 Rubber: 5,6 to 6,0

Paving grade bitumen: 4,6 to 4,9

Fibers: 5,2 to 5,8 Rubber: 5,9 to 6,15


ρ = 2,75 g/cm3




Richness Modulus K 3,3 3,4

Binder content TLext for a granular mix mass density

ρ = 2,75 g/cm3


Paving grade bitumen: 4,6 to 5 Fibers: 5,3 to 5,9 Rubber: 6 to 6,3

Category 2

PA10-BBDr2 (%)

PA6-BBDr2 (%)


ρ = 2,65 g/cm3

Paving grade bitumen: 4,2 to 4,6 Fibers: 4,9 to 5,2 Rubber: 5,3 to 5,7



K 3,2 3,1

3.3.4 Thin asphalt mixes – AC-BBM, BBTM and mixes for UTLAC (BBUM)

Figure 25: Cross-section of a Thin Layer Asphalt Concrete (AC-BBM)

Figure 26: Surface appearance of a Thin Layer Asphalt Concrete (AC-BBM)


- 96 -


Aggregates The observations forwarded above for the porous asphalt (PA-BBDr) mixes would also apply Thin Layer Asphalt Concrete (AC-BBM), Very Thin Layer Asphalt Concrete (BBTM) and Ultra-Thin Layer Asphalt Concrete (UTLAC or BBUM) families. By lowering the percent passing at 2 mm, porosity increases as does the mean texture depth (MTD).

Binders and additives The binder may be either a 50/70 or 35/50 grade pure bitumen or a polymer-modified bitumen. The Thin Layer Asphalt Concrete (AC-BBM) family of mixes often contains pure bitumen. When rutting resistance is targeted, it is advised to select a bitumen with enhanced thermal susceptibility and to add polyethylene or use a modified binder. BBTM mixes are produced with either pure or modified bitumen and without providing objective selection criteria (the texture loss test, which had been listed in the previous version of the standard, did not offer distinctive insight on this particular point). The use of cellulose or glass fibers in BBTM mixes is intended to improve the (empirical) quality of the mortar.


The initial particle size distribution curves for Thin Layer Asphalt Concrete (AC-BBM) and BBTM are provided in Table 29 below. The texture and open appearance of these mixes are influenced by the percent passing the 2-mm sieve. Types B and C of the AC-BBM family are rarely applied, yet they adapt well to flexible pavements submitted to light traffic loads.


- 97 -

Table 29 – Initial AC-BBM and BBTM grading curve

Sieve percent passing

D Gap-graded

fraction 14 10 6,3 4 2 0,063

AC-BBMA 10 2/6 97 35 30 - 32 6,5 - 7,2

Not advised ⇒ 14 2/10 97 35 35 7,2

AC-BBMA 14 4/10 97 35 35 7,2

AC-BBMA 14 2/6 97 67 35 34 7,2

AC-BBMB 10 Continuous 97 53 53 38 10

AC-BBMB 14 Continuous 97 75 50 50 35 10

AC-BBMC 10 Continuous 97 53 53 38 7,2

BBTM, Category D 10 2/6 30 25 - 35 5,5 to 6,5

BBTM, Category A 6 2/4 30 28 - 35 7,0 to 8,0

10 2/6 25 18 - 25 5,0 to 6,0 BBTM, Category B 6 2/4 25 20 - 25 5,0 to 6,0

Sieve percent passing

Gap-graded

fraction 14 10 6,3 4 2 0,063

10 Continuous 30 25 - 35 7,0 à 7,5 BBTM, Category A 6 Continuous 30 30 - 35 7,0 à 8,0

10 Continuous 25 18 - 25 5,0 à 6,0 BBTM, Category B 6 Continuous 25 20 - 25 5,0 à 6,0

3.3.4.3 Bitumen content Bitumen content to start the mix design, is calculated from the specific surface area of the mix, the maximum density (MVR) value and the minimum richness modulus.

Table 30 below presents internal binder content (according to EN Standard) with a maximum density (MVR) of aggregate 2,65 g/cm3 for AC-BBM, BBTM and mixes for UTLAC (BBUM); the external binder content (application according to former French Standard) with a maximum density (MVR) of aggregate of 2,75 g/cm3, is also mentioned.


- 98 -

Table 30 – Initial AC-BBM, BBTM and mixes for UTLAC (BBUM) binder content

AC10-BBM A

AC14-BBM A

BBTM10

Class A or D

BBTM6 Class A

BBTM10 Class B

BBTM6 Class B

Binder content Bint for a granular mix mass

density ρ = 2,65 g/cm3

5,4 5,2 5,6 – 6,05 6,05 – 6,5 4,5 – 5,4 5,4

Binder content TLext for a granular mix

mass density ρ = 2,75 g/cm3

5,5 5,3 5,7 – 6,2 6,2 – 6,7 4,5 – 5,5 5,5

0/10 UTLAC (BBUM) 0/6 UTLAC (BBUM)

Binder content Bint for a maximum aggregate density ρ = 2,65 g/cm3 4,95 – 5,7 5,7 – 6,2

Binder content TLext for a maximum

aggregate density ρ = 2,75 g/cm3

5 – 5,8 5,8 – 6,4

3.3.5 Stone Mastic Asphalt - SMA

Figure 27: Cross-section of an SMA (Stone Mastic Asphalt)

Figure 28: Surface appearance of an SMA (Stone Mastic Asphalt)


- 99 -


Binders and admixtures SMA generally contain fibers. It should be remarked that with the inclusion of fibers, the mix design that yields bitumen content on the basis of richness modulus is not considered valid.

3.3.5.2 Composition of the granular mix The initial particle size distribution curve for SMA is indicated in Table 31 below.

Table 31 – Initial SMA grading curve

D 10 8 6.3 4 2 0.063

10 92 57 - 62 39 - 44 30 - 34 25 (20 to 35)

11 (5 to 13)

SMA

8 100 96 73 40 27 (20 to 40)

12 (5 to 14)

3.3.5.3 Binder content and fiber content The bitumen content at the beginning of this study is shown in Table 32 below, calculated in two ways:

- internal binder content (according to EN Standard) with a maximum density (MVR) of aggregate equal to 2,65 g/cm3;and

- for information, external binder content (application according to former French Standard) with a maximum density (MVR) of aggregate of 2,75 g/cm3, characteristic of an average French value;

To complement this input, Appendix C provides the correspondence table between external and internal binder content, calculated for an identical mass density of 2,65 g/cm3.

Table 32 – Initial SMA binder content

SMA 10 SMA 8

Binder content TLint for a maximum aggregate


6,8% with 0,3% cellulose fibers


Binder content TLext for a maximum aggregate


7% with 0,3% cellulose fibers


3.4 Composition adjustments Based on the standard grading curves defined for each material, the mix designer seeks to obtain the percentage of voids specified for each product (see Table 9). For


- 100 -

this step, the mix is typically submitted to the Gyratory Compactor test (or another designated test). If the expected result is not the one ultimately obtained, the mix designer must modify the composition, which requires understanding the effect of composition variables.

3.4.1 Effect of mix variables (general remarks) The mechanical characteristics of the mix stem from the combined effect of internal friction on the granular skeleton, binder content and binder characteristics (including the additives eventually introduced).

3.4.2 Effect of dimension D If D were to be increased, the richness modulus (and thus binder content) would have to drop. With all other parameters held unchanged, by increasing D, the percentage of voids in the mix decreases. As the D value of the mix rises, it becomes easier to obtain a stable material, yet attention must then be paid to the risk of segregation during placement.

– Example –

A AC10-BBSG mix with 5,6% bitumen is equivalent to a AC14-BBSG with 5,4% bitumen.

A AC10-BBSG with 5,6% bitumen leads to a percentage of voids at 60 gyrations V60 = 9%, while a AC14-BBSG with 5,4% yields a characteristic percentage of voids at 80 gyrations V80 = 4%.

3.4.3 Effect of granular proportions With greater granular fractions, mix design setting becomes facilitated. For a 0/D mix with 10 mm < D < 20 mm, the percent passing at 2 mm can display one of the four following cases:

• > 35% percent passing at 2 mm very high curve: mortar content is in excess within the granular skeleton and stability relies solely upon the mortar.

• 30 to 35% percent passing at 2 mm high curve: the mortar fills nearly all inter-aggregate space. The mortar plays a key role in overall mix characteristics.

• 25 to 30% percent passing at 2 mm average curve: coarsely-graded design. Mortar influence is attenuated due to effect of the granular skeleton.

• < 25% percent passing at 2 mm low curve: the mortar exerts a secondary influence, with mix stability obtained by means of inter-aggregate setting.

3.4.4 Discontinuity A discontinuity (gap-grading) within the particle size distribution curve leads to an increase in workability along with a drop in percentage of voids, although the rutting risk rises as a result.


- 101 -

– Example –

A AC14-BBSG or a AC14-BBM with a continuous curve yields a rut depth of 3 mm at 30000 cycles. The rut extends to 4 mm with a 2/6 discontinuity and to 10 mm with a 2/10 discontinuity.

Should the material be used as a thick layer, it would be preferable to apply a gap-graded curve with a relatively low threshold, e.g. 25% at 2 mm.

3.4.5 Incorporation of rounded particle aggregate The inclusion of rounded particles, generally limited to 10% for wearing courses, serves to increase mix workability while reducing the percentage of voids. On the other hand, the risk of rutting naturally rises quite considerably as a consequence. This type of mix formulation is not be used on roads submitted to heavy traffic loads. For AC-EME or AC-BBME however, blunt-edged materials, and in particular fine aggregate with totally rounded particles, may be used to enhance compacity, with binder stiffness serving to reduce the risks of rutting. Yet when employing such an approach on surface materials, the durability over time may be compromised.

3.4.6 Percentage of fillers Fillers, in combination with bitumen, make it possible to fill the inter-granular voids. As total filler percentage increases, the percentage of voids in the mix will drop, but the mastic will harden. The optimal value lies between 6,5% and 7,5% for average curves and typical bitumen contents.

3.4.7 Percentage of bitumen Bitumen, when combined with fillers, plays the role of lubricant for the granular skeleton and thus enables compacting the material. Beyond an optimal content, its function is limited to filling voids in the granular skeleton. As the percentage of bitumen increases at low bitumen content levels, the stiffness modulus rises as well; whereas with higher bitumen content, this modulus tends to fall. As the percentage of bitumen increases, the inter-granular mastic film becomes denser and thicker, which makes for improved fatigue and water resistance, with the downside being that rutting resistance decreases. These trends have been laid out under very general conditions. In practice, certain mix component characteristics can modify expected behavior. As an example, it would be necessary to incorporate the effect of absorbent materials (porous aggregates, fibers).

3.5 Gyratory Compactor compactibility study

3.5.1 General remarks The test is conducted on a composition (test interpreted in isolation) or on an experimental design (2 or 3 different granular compositions) containing, for example, a 5% deviation in the fine aggregate concentration.


- 102 -

This test is to be interpreted in two ways; first, it seeks to verify the type testing criteria (v% at 60, 80, 100… gyrations as specified vs. the thickness of the layer under consideration) in comparison with the standard, should one exist. Secondly, the test is intended to make use of the entire set of data available to predict one behavioral aspect of the mix or another. The Gyratory Compactor test is quite sensitive to: granular composition, including the fines fraction; angularity of the mineral skeleton; and binder content. Upon completion of the Gyratory Compactor tests, the mix designer must be able to introduce enough elements to establish both the particle size distribution curve and binder content. The primary parameters to be interpreted are the following:

percentage of voids vs. number of gyrations; percentage of voids at a given number of gyrations; percentage of voids at 10 gyrations; percentage of voids at 1 gyration; slope K1; and pseudo-maximum shear stress.

3.5.2 Percentage of voids vs. number of gyrations The evolution in compaction using the gyratory compactor, v% = f(ng), was studied at the same time on a full-scale compaction bench [Moutier, 1977; Bulletin de liaison LPC, Special Issue V, p. 173-180]. This compaction bench contained an axle capable of being loaded up to 50 kN per wheel, with tire pressure varying from 0,3 to 0,9 MPa. Production was routed through a reduced-scale mixing plant and placement handled by a small finisher. The experimental design focused on three thickness ranges: 4 cm, 8 cm and 12 cm. For each of these ranges, three different mix designs were introduced: – in 4-cm thickness: AC10- BBM with rounded fine aggregate, AC14-

BBM (2/10 and 4/6 gap-graded) (solid mineral aggregates N); – in 8-cm thickness: "coarse" AC14-BBSG; "semi-coarse" AC14-

BBSG, discontinuous AC14-BBSG (solid mineral aggregates N); and – in 12-cm thickness: AC20-GB2 with aggregates from three different

solid rock origins: microdiorite, quartzite and alluvial deposits. Experience has shown that percentage of void trend curves vs. number of gyrations and vs. number of compactor passes are quite similar. On the v%= f(ng) and v%=f(np) graphs, with a semi-logarithmic scale for the number of gyrations or compactor passes, the evolution is nearly linear.


- 103 -

A sigmoid model (S-shaped) was applied to the v%=f(ng) curve in order to deduce extreme clamping behavior at a very high number of gyrations (curve asymptote). This model is relevant for the range of materials tested (AC-BBSG, HRA, AC-BBM). The compacity of the granular skeleton submitted to high energy levels tends to a limit, denoted C∞; this compacity value is greater than those obtained at typical gyration thresholds (< 200) and suggests that even for very angular mixes, an additional "clamping potential" remains over and above current specifications. Such potential can be realized during exceptional climatic or traffic conditions.

Modeling of Gyratory Compactor results - Assessment of ultimate compaction threshold, F. Moutier, Eurasphalt & Eurobitume Conference '96

3.5.3 Percentage of voids at a given number of gyrations Comparing the percentage of voids measured on specimens generated from the studied plates for a "standard" compaction mode (approximately 16 passes) with that derived using the gyratory compactor by direct geometric measurement has demonstrated that: for mixes applied in 4-cm thickness, the corresponding percentage of voids was obtained at 40 gyrations; and for 8-cm thick mixes, 80 gyrations were required to reach this void level. Experimentation conducted on 12-cm thick material samples proved less conclusive. The 40-gyration relationship for the 4-cm material (AC-BBM and PA-BBDr ranges) and evaluation at 80 gyrations for materials spread over 8 cm (AC14-BBSG or AC14-BBME) initiated adoption of the French specifications. Following a few extra experimental findings, this relation was generalized: 25 gyrations for 2,5-cm thick BBTM; 60 gyrations for AC10-BBSG or AC10-BBME spread 6 cm thick; 100 gyrations for AC14-GB or AC14-EME ( high modulus mixes) applied approximately 10 cm thick; 120 gyrations for AC20-GB or AC20-EME applied approximately 12 cm thick. These percentage of void ranges, associated with gyration number vs. layer thickness, have become laboratory specifications, aimed at predicting the percentage of voids attained on the jobsite. The predictive capacity of the percentage of voids parameter at n gyrations had been analyzed as part of a survey entitled: "Gyratory compactor testing assessment" within the LPC research network [Ballie, Delorme, Hiernaux and Moutier, Bulletin de liaison LPC, Issue no. 170]; this work showed that the value identified in the laboratory tended to be somewhat pessimistic for the Grave-Bitume AC-GB and AC14-BBSG, evenly valued for AC10-BBSG and more optimistic for thinner mixes. These relations depend on trends tied to: material mix design (e.g. cessation of the use of rounded materials), mix production mode (drum mixers), and type of spreading and compaction (vibratory compactors). Such factors need to be incorporated whenever the value targeted for a jobsite is deduced on the basis of a laboratory-determined percentage of voids. A study on crushed bituminous aggregate, high modulus mixtures and semi-coarse bituminous concretes has been carried out (see Section 4.1) in order to verify the correspondence between the percentage of voids measured: on laboratory materials (representative of worksite conditions), on materials extracted from onsite mixing plants using a mobile gyratory compactor, and onsite by means of gamma-densitometers. With the exception of one site where production uncertainties led to under-compaction, the average results obtained at each stage were for the most part similar (maximum deviation: 1,4%).


- 104 -

3.5.4 Percentage of voids at 10 gyrations: v10

The percentage of voids at 10 gyrations represents the state of the material submitted to very weak energy. The kind of mix that when exposed to such weak energy yields a low percentage of voids would actually display excessive workability; it is likely that this result stems from weak internal friction of the granular skeleton, wherein lies the potential risk among more ordinary mixes (AC-BBSG, AC-GB, etc.) of offering only limited resistance to rutting. This risk gets taken into account in the specifications on certain products, whose threshold has been set lower (9% to 14%). Such a criterion was selected within the scope of EN standards, yet due to its empirical relation with rutting resistance cannot be imposed at the same time (overspecification).

3.5.5 Percentage of voids at 1 gyration: v1

v1 denotes the percentage of voids calculated at one gyration (or C1 the compacity at one gyration) in accordance with the equation model set forth in the EN 12697-10):

v% = v1 - K1 ln(ng) or ( )ngKCC ln% 11 +=

The model is then adjusted with respect to a regression line for points (v, ln(ng)) or (C, ln(ng)) lying between 20 gyrations and 200 gyrations. V% is computed by considering that compaction using the Gyratory Compactor is linear as a function of the logarithm of the number of gyrations. The percentage of voids at 1 gyration also serves as a rutting resistance indicator (for the same reasons as for v10). The 20% threshold (AC-GB, AC-BBSG) seems to provide a satisfactory estimation.

3.5.6 Slope K1

The slope K1 in the model v% = v1 - K1 ln(ng) is sometimes referred to as the mix workability indicator. Its value is more heavily correlated with the upper sieve size D of the mix. Should bitumen content vary over narrow ranges, K1 would stay constant for a given granular skeleton. On the other hand, K1 varies whenever the fines content varies.

K1

1

v1 ng

200

0

20


- 105 -

Granular compacity does not vary any further for bitumen contents above 4%. An increase in bitumen content is equivalent to filling the inter-granular voids.

For a binder content variation of δTL, compacity C1 becomes C2, i.e.:

( )03,1)100(

100100

1

112 xTL

TLMVRCC

+××

+×≈δ

(The variation of maximum density (MVR) has been neglected herein.)

3.5.7 Pseudo shear stress τ The pseudo shear stress τ is defined as the force necessary to straighten the specimen submitted to gyratory compaction at a small internal angle (0,82°).

τ is defined by the following relationship: ShdF

××

= 11τ ;

F1 is the force necessary to maintain the Gyratory Compactor angle, expressed in Newtons;

d1 is the distance that force F1 acts with respect to the specimen axis, in millimeters;

h is the specimen height, in millimeters; and S is the surface area of the specimen base.

On the LPC gyratory compactors of types 1 and 2, hF101,0≅τ (in MPa).

The evolution in τ has been tracked vs. percentage of voids v%. At the maximum τ value, τmax, the value of v%(τmax) corresponding with this maximum is obtained.

% Voids

τmax τ

v % (τmax)


- 106 -

The variations in τ as a function of v% depend on the type of mix. As an example, for AC-EME or BBTM, the curves exhibit the following shapes:

⎯ v%(τmax): The percentage of voids corresponding to the value of τmax constitutes a lower bound of the mix design application range (i.e. the critical percentage of voids). Beyond this limit, the mix loses its stability (presence of rutting risk).

⎯ τ might be correlated with vfb < 65% or 75%.

3.5.8 Test precision

Percentage of voids at a fixed number of gyrations: Repeatability: r = 0,95 Reproducibility: R = 1,38 r and R represent the critical distance separating two test results under conditions of either repeatability (same laboratory, same sample, same operator, short time interval) or reproducibility (with different laboratory and operator). Should the distance between any two results lie below this critical distance, results could not be considered as distinct.

3.5.9 Correction of mix composition

The effects of mix composition factors on the Gyratory Compactor test results were studied within the framework of an experimental design that includes upper sieve size of the mix, factor D, the bitumen percentage, factor B, the percentage of fines factor F and the compacity (or void content) factor C; the primary set of results of this experimental study DBFC will be presented next.

τ

v % (τmax)

AC-EME τmax

% voids

v % (τmax)

BBTM

τmax

τ


- 107 -

Example – Impact of mix design factors on Gyratory compactor test results (solid mineral aggregates N)

Experimental plan DBFC: Impact of factors D (mm), binder content B (%), filler content F (%) on the mix compacity:

D, B, F have a significant effect on C80

D, B have a significant effect on C1

D, F have a significant effect on C1

Effect of binder content B on C1

68,00

70,00

72,00

74,00

76,00

78,00

80,00

4 6 8binder content (%)

C1

(%)

effect of D on C1

71,00

72,00

73,00

74,00

75,00

76,00

77,00

78,00

6 8 10 12 14 16 18 20 22D mm

C1

(%)


- 108 -

effect of filler content F on C80

82

82

83

83

84

84

85

85

86

86

87

87

4 8 12Filler content (%)

C80

(%)

effect of D on C80

81

82

83

84

85

86

87

88

89

6 8 10 12 14 16 18 20 22

D mm

C80

(%)


- 109 -

These composition parameter effects were examined on "test" mixes for purposes of the experimental design, with mix compositions not always corresponding to those actually employed on road-building sites. While the experimental design has served to confirm major well-known trends practiced by mix designers, testers were questioned about their own experience, and this step gave rise to the contents shown in Table 33:

Table 33 - Composition effect on Gyratory Compactor test results

Trends in composition parameter effects on Gyratory Compactor test results Parameter Effect (%vng) Observations

Bitumen content – 0,25 + 0,5 to + 0,6 See water resistance

Bitumen content + 0,25 - 0,5 to – 0,6 See rutting resistance

Fines content + 1 - 1,7 to – 0,5

Fine aggregate volume + 10% - 1

Passing the 2-mm sieve + 5% - 1 to – 1,5%

2/4 discontinuity (at a constant fine aggregate %) - 1

2/6 discontinuity (at a constant fine aggregate %) - 3

4/10 discontinuity

Mastic volume 16% -> 23% + 4%

+ 10% rounded fine aggregate - 1,5 to - 2 Potential rutting

effect of binder content B on C80

78

80

82

84

86

88

90

4 6 8Binder content (%)

C80

(%)


- 110 -

Table 34 - Composition adjustment in order to correct Gyratory Compactor results

Adjustments to the composition to ensure that Gyratory Compactor voids are positioned within the target window

Much lower than the target % (by > 5%)

Lower than the target % (by 3%)

Above the target % (by 3%)

Considerably above the target % (by > 5%)

decrease the % passing the 2-mm sieve

by ~ 5 points and increase the 2/6,3

fraction

decrease the bitumen %

and

decrease the % of total fines by 1,5% to 2,5%

decrease the 2/6,3 fraction on the order of 10% and increase the

6,3/10 fraction

increase the % passing the 2-mm sieve by

~ 5 points and decrease the 2/6,3

fraction

introduce ground fine aggregate at a level of 10% or 15% (focus on

rutting resistance)

or

rounded fine aggregate at a level of 10% (focus on rutting resistance)

3.6 Mix performance

3.6.1 Resistance to permanent deformation on the LPC Wheel Tracking Tester

3.6.1.1 Purpose

The objective herein is to verify that the mix actually exhibits the behavior expected during the compactibility study phase. The effect of both binder type and admixtures is to be taken into account as well. The test is conducted on 2 plates at a required level of compacity and leads either to reaching the specified level of compacity, thus making the results directly interpretable, or to repeating a 2-plate series at a compacity level such that the two values obtained frame the intended result. If the new series lies within the prescribed range, the rut depth can be interpreted directly, whereas if the percentage of voids lies outside this range, the wheel tracking test result at the target value is to be found by means of linear interpolation. Example: For a AC-BBSG, the interval specified in the standard is 5% to 8% voids. If the first attempt leads to 3% voids, the second will aim for a position around 7%. If a figure less than 8% is actually obtained, the result may be determined directly. Otherwise, with 10% voids for example, the following operation is performed: Linear interpolation between the rut depth at 10% voids (i.e. 7%) and the depth measured at 3% voids, i.e. 12%. The interpolated result at 6,5% voids amounts to 9,5%.


- 111 -

The interpolated value obtained using this method is "pessimistic" from a safety standpoint in comparison with the experimental value, which lies close to 5% in the above example. The result must satisfy a rut depth threshold (with respect to plate thickness), i.e. 5%, 7,5% or 10% at a given number of cycles: 3000, 10000, 30000. Remarks: In order to preserve a safety margin, the test may be conducted for a binder content increased by 0,25% or with a "softer" grade bitumen than that of the prescribed bitumen. Generally speaking, the percentage of voids estimated from a test plate corresponds: - for weak compaction low in percentage of voids with the Gyratory Compactor at 40

gyrations, - for strong compaction high in percentage of voids at 120 gyrations. One deviation

with respect to this estimation may be the indicator of a workable or, alternatively, rough mix.

Another practice consists of adopting 10% voids for weak compaction and 5% for strong compaction with ordinary mixes.

3.6.1.2 Results interpretation

Rut percentage Less than 10% at 30000 cycles constitutes, for mix designs with a continuous grain size distribution, a widely-recognized limit to indicate that the mix is not at risk of rutting under harsh use conditions. Less than 5% at 30000 cycles constitutes a widely-recognized limit to indicate that the mix is not at risk of rutting under very harsh use conditions. An intermediate category at 7,5% was introduced for several mix products (AC-BBSG, AC-EME, AC-BBME).

9,5

12

7

Trend curve estimated from the rut depth

slab voids %

3 6,5 10 5 8

5

Specified range

Interpolated value

Rut depth, %


- 112 -

Under exceptional loading conditions, a test can be performed at 65°C, with a 6-kN vertical force, and ultimately in including a metallic wrapping. No reference data are currently available on any such test.

Curve shape With some modified binders, the lg(P%) = lg(number of cycles) curve suddenly veers at around the 3000-cycle mark; one plausible explanation for this phenomenon was sought, with the conclusion being that localized parasitic heating could constitute the cause. Based on experimental data, it is possible to identify the parameters A and b of a deformation law of the following form:

Y = A (N/1000)b This approach no longer appears in the EN standard.

3.6.1.3 Special case of the "mechanical stability" test

For very thin layer asphalt concretes BBTM, a "mechanical stability" test may be carried out by employing the rutting test operating protocol. This test is not of the rutting type per se, but instead is intended to characterize the capacity of the mix to "close" and spread smoothly in rolling strips. The rut depth criteria can thus be stated as: 3000 cycles = 15% (0/10 BBTM) and = 20% (0/10 BBTM).

3.6.1.4 Influential parameters

Table 35 lists the composition parameters capable of influencing the rutting test result and their effects. Table 36 then summarizes the advice of practitioners for raising rutting resistance.


- 113 -

Table 35- Effects of mix design factors on % rutting

Example of effect of composition parameters on rutting test results Parameter % rutting Observations

Bitumen content: 0,2% increase At 3000 cycles, the rut depth expands from 5,5% to 9,6%

Bitumen content: 0,2% decrease At 3000 cycles, the rut depth declines from 5,5% to 3,9%

Fines content: 0,8% increase No noteworthy effect

Transition from 70/100 grade to 35/50 grade

At 10000 cycles, the rut depth drops

from 5,5% to 3,2% Bitumen grade

7°C rise in TR&B Rutting resistance increases by a set of ten cycles

At 10000 cycles, the rut depth of a AC-BBSG is scaled back:

CASE 1 from 14% to 10%

CASE 2 from 12,3% to 7,5%


Strong rise in angularity:

Ic 30 to Rc 2

CASE 4 from 12% to 6,2%

at 10000 cycles, the rut depth of a crushed bituminous aggregate declines:


Small rise in angularity:

Ic 80 to Ic 100 (Former

approach of angularity => C90/1 to C95/1)

CASE 2 from 6,3% to 3%

The compacity effect alters the

result.

+ 10% rounded fine aggregate

At just 1000 cycles, the rut depth jumps from 3% to 10%.

Angularity

Replacement of crushed

fines by ground fines

For a % passing the 2-mm sieve on the order of 33%, rut depth increases from 7,5% at

30000 cycles to 10% at 3000 cycles.

Table 36 - Practitioners' advice - Enhancing rutting resistance

Wheel tracking - Rut depth

Greater than the target value > 2% above target value Observations

− "Indent" the curve − Lower binder content − Use bitumen with a higher ring and

ball temperature − Use admixtures

− Use bitumen with a ring and ball temperature and apply admixtures, PE, etc.

− Use a special bitumen with greater thermal susceptibility

− Change the fine aggregate

Beware of the risk of top-down cracking, if applicable (hard grade + low bitumen content)


- 114 -

3.6.2 The Duriez test (Method B of EN 12697-12) The Duriez test procedure is described in part B of EN 12697-12 ITSR. In this standard, the specimens may be compacted using several methods (gyratory, impact, core…). The results considered in this clause are obtained with specimens compacted in compression by application during (300 ± 5)s of 60 kN ± 0,5 % for specimens of which diameter is less than 100 mm or 180 kN ± 0,5 % for other dimensions.

3.6.2.1 Purpose

This test is intended to verify water resistance. It does however serve to approximate the mechanical characteristics and percentage of void values submitted to static compaction.

3.6.2.2 Interpretation

I/C (r/R) value The typical values of I/C (r/R) lie between 0,65 and 1,0.

Example for porphyries from Boulouris (south of France)

This quarry mines an eruptive deposit principally characterized by the very strong CPA reading (> 0,55), corresponding to a PSV of 57; the cleanliness of the fine aggregate complies with the "a" category: Vbta lies on the order of 1 g/100g, i.e. for an MBF on the order of 1000 g/kg.

Despite these findings, it was proven that the use of fine aggregate and, in some instances, coarse aggregate lead to generally noncompliant water resistance values, as shown in the following examples:

Mix design Binder (% out of the i i )

Additive I/C (r/R) AC20-GB all porphyry 5,5% of 35/50 / 0,53

AC20-GB all porphyry 6,0% of 35/50 / 0,73

AC10-BBSG 5,9% of 35/50 / 0,71

Fine alluvial aggregate, coarse porphyry aggregate 6,2% of 35/50 / 0,79

6,6% of 13/40 Styrelf / 0,68 BBTM6

7% of 13/40 Styrelf / 0,72

Fine alluvial aggregate 7% of 13/40 Styrelf 0,3% Cecabase S 240 PF 0,78

4/6 porphyry 7% of 13/40 Styrelf 0,6% Cecabase S 240 PF 0,80

I/C (r/R) ratio values greater than 1 are to be correlated with problems of bitumen absorption by aggregates. Using mixes rich in coarse aggregate, e.g. drainage mixes, aggregate failures may arise during specimen production. The I/C (r/R) value is thus less than 0,8.


- 115 -

For some granite materials, water resistance must still be verified.

Compressive strength I/C Table 37 - Typical I/C values (in MPa)

Bitumen category AC-GB AC-EME BBTM PA-

BBDr AC-

BBME AC-BBSG AC-BBM

50/70 6 to 9 7 to 9(*) 5,1 to 7,1

35/50 9 to 14 6 to 10 2 to 4 6 to 14 (typical: 9-10) 6,6 to 12,1

< 25 12 to 21 (*) Mix designs composed of pelite coarse aggregate and limestone fine aggregate have yielded a compressive strength of 12,1 MPa.

Percentage of voids: This parameter is to be compared with the percentage of voids using the Gyratory Compactor for n gyrations. On the AC-BBSG material, the percentage of voids lies on the same order of magnitude. If the level of deviation amounts to 3% or 4%, the material is said to be "frictional".

Percentage of imbibition: This parameter is used in evaluating the swelling nature of the material and has been defined by:

M: mass of the dry specimen, Mj+1: specimen mass after degassing (1 hour without immersion

+ 2 hours with immersion), Mj+k: specimen mass after k days of immersion.

The percentage of imbibition is defined using: Wj+k= 100*M

MM kj −+

Threshold value: ===> 2% The swelling (increase in specimen volume) goes hand in hand with low I/C (r/R) ratio values, through observations on materials such as polluted limestone or water-sensitive solid rocks.

Adjustment of results

Table 38 - Practitioners' advice - Duriez test results adjustment

I/C ratio Duriez

Below the targeted value Much lower than the targeted value

− bitumen enhancer within the mass (extra 0,3%-0,6% compared with the original bitumen)

− use of fines activated by 20% quicklime or slaked lime

− increased richness modulus (with decrease in the % passing the 2-mm sieve)

− introduction of a harder grade bitumen − higher compacity through a drop in the 2/6 fraction

− contribution of 1% quicklime or slaked lime

− replacement of all or part of the fine aggregate proportion by fine aggregate from another origin


- 116 -

Remark: Stability of the additive (enhancer) within the hot binder: Example of Cecabase S240 PF on a 0/6 BBTM material: I/C (r/R) = 0.72; with 0.3% enhancer held 48 hours at the production temperature, the I/C (r/R) ratio remains roughly the same: 0,75. With 0,6% additive (enhancer) and under this same set of conditions, the I/C (r/R) ratio equals 0,8.

3.6.3 Stiffness modulus

3.6.3.1 General comments Determination of the stiffness modulus requires longer tests that typically extend beyond the mix design context. For certain materials (e.g. AC-EME), it nonetheless proves necessary to know the mix stiffness modulus in order to ensure that specifications are being met. Depending on possibilities available in the laboratory, various stages of experimental designs can be developed using either the direct tensile test or the complex modulus test.

⎯ Complex modulus: It is possible to derive a rough design by directly conducting a test at 15°C / 10 Hz.

⎯ Modulus determination test in direct tension (MAER): Modulus at 15°C and 0,02 sec: this modulus value is greater than or equal to the complex modulus at 15°C / 10 Hz. For AC-EME in particular, the direct tensile modulus often exceeds the complex modulus.

Regarding the contour of the index curves at a given temperature, in the absence of experimental values, the time-temperature equivalence principle may be applied along with the following relation:

aT(T,Ts) = exp [ )]11(TsTR

H−

∆

∆H: in the vicinity of 50 kcal/mole R: perfect gas constant = 8,35

3.6.3.2 Effect of mix design factors

The variations in stiffness modulus vs. compacity variation ∆C may be approximated by means of the following equation where Tlext is the binder content “out of the mix”:

∆E = (2,000 – 310 TL ext) ∆CTLext (Equation established with solid mineral aggregates N and a 40/50 bitumen)

The bitumen content effect may then be approximated using this equation:

∆E = (18,000 – 3,700 TL ext) ∆TLext


- 117 -

(Equation established with solid mineral aggregates N and a 40/50 bitumen)

Example: Impact of mix design factors on the direct tensile modulus

Effect of F on the modulus 10°C,0,02s

6,00

6,50

7,00

7,50

8,00

8,50

9,00

9,50

4 5 6 7 8 9 10 11 12

Filler content

mod

ulus

10°

C,0

,02s

3.6.3.3 Loss of linearity

The loss of linearity Γ, as defined in the test standard, is determined for a 30-second loading time and 0°C temperature.

Γ is a first-loading damage indicator and tends to be correlated with microcrack formation in the mix; for this reason, a correlation with fatigue resistance could be derived (see Section 3.6.4). With stiff materials, such as AC-EME, material fractures are observed prior to reaching the 500 µdef threshold.

3.6.3.4 Direct tensile modulus - complex modulus equivalence relation

Theoretical formulae have been developed to correlate modulus values E(θ,t) and E(θ,f). At 10°C or 15°C, the modulus values for a 10-Hz frequency and 0,02-sec loading time may be considered as equivalent. This equivalence has been experimentally verified to a large extent. Deviations have however been detected on certain materials [up to 4000 MPa].

Example of experimental relationship between E15°C 10Hz and E15°C 0.02 s:

168,15989,0 02.0151015 −×= °° sCHzC EE

974,02 =R

[RILEM '97, Lyon - p. 225]


- 118 -

3.6.3.5 Estimations of mix modulus values

The stiffness modulus of the mix may be estimated by means of empirical equations through the introduction of a range of approximations.

Ugé's method:

( )23 2135,068,5108 vgVgSmIg ++= −

[Bitumen and asphalt mixes, BL.NSV] For bitumen samples with a stiffness modulus value Sb (expressed in MPa) either measured or determined using the Van Der Poel abacus, the mix modulus can be estimated by employing the nomograph shown in Figure 29 with respect to bitumen volume Vb and aggregate volume VG.


- 119 -

Figure 29: Nomograph for calculating mix stiffness modulus values


- 120 -

The stiffness modulus values generated using this method may deviate from experimental values by a factor of 2. Shell method: Estimation of the bitumen modulus (Péné + TBA); computation of the mix modulus based on granular compacity and loading time or frequency). The standard modulus calculation formula is given by:

n

v

vbm C

Cn

SS ⎥⎦

⎤⎢⎣

⎡−

×+=1

5,21 , in MPa.

Sbn

4104lg83.0−×

= and VbVg

VgCv +=

This relation is applicable to highly compact mixes (≅ 3% voids).

For other asphalt mixes, Cv is replaced by 3100

100'

−+×

=vC

C vv

with v = percentage of voids. Francken's method: The elastic modulus ∞E is calculated (for low temperature and high frequency values):

( )21081,555,0

410436,1−×−×⎟

⎠⎞

⎜⎝⎛××=∞ e

VbVgE , in MPA

Vg: aggregate volume in the mix, Vb: binder volume in the mix, v: percentage of residual voids in the mix.

The complex modulus *E is proportional to the elastic modulus via the "reduced modulus R*" function:

∞= xERE **

R* depends on the bitumen consistency at a given temperature and frequency, as

expressed by G* and the VbVg ratio on the following graph:


- 121 -

These methods do not account for the effect of aggregate type.

3.6.4 Fatigue

3.6.4.1 General comments

The fatigue test is not performed as part of the mix development stage. It is still possible however to estimate fatigue resistance values by means of empirical relationships. Keep in mind that these assessment formulae are invalidated by changing the type of bitumen and must therefore be used as a relative gauge.

3.6.4.2 Prediction based on the direct tensile test

( )( )sEAAA 300,02104

6 110 ×+Γ−+= −ε

Γ is the loss of linearity, and E0,300s is the modulus at 0°C and 300 sec.

The relationships between fatigue resistance ε6 and loss of linearity Γ have been obtained from two databases, built by R. Linder and F. Moutier, respectively.

Table 39 - Fatigue - loss of linearity relationship

LINDER coefficients MOUTIER coefficients Pure bitumen

Ao 2,69 2,39

A1 5,24 3,30

A2 8,71 10-6 -

Confidence interval on ε6 (MOUTIER coefficients) + 0,26 10-6 (for approximately 40 mix designs).


- 122 -

3.6.4.3 The Shell prediction method (Shell pavement design methods, 1978)

ε6 may be estimated from the following equation:

( )36,0

66 0005

224.1710−

−⎟⎟⎠

⎞⎜⎜⎝

⎛×+××= m

bSVε

Vb: bitumen volume, expressed in %, and Sm: stiffness modulus of the mix, in MPa.

3.6.4.4 Francken's prediction method (fatigue test with imposed stresses)

021,0 σε −= KN

vmbbK

+= Λ

Λ : depends on both the thermal susceptibility B’ of bitumen and bitumen penetration at the loading time,

b: binder volume,

( )100/mayvm =

b/(b+vm) is the percentage of voids filled by the binder.

3.6.4.5 LPC method

The ε6 value for bitumen content TL with respect to compacity variation ∆C for bitumen content TL can be approximated by the following equation:

( ) C∆=∆ 3,36ε

( ) 626 103,385,472125 −∆+−+−= CTLTLε

This equation was established for solid mineral materials N with mass density 2,85 g/cm3 and a 40/50-grade bitumen.

3.6.4.6 Formula adjustment to improve fatigue resistance

For binder contents below 7%, fatigue resistance rises with bitumen content [a 1% increase in bitumen content offers the potential of gaining 25 µdef on the value of ε6].

3.6.5 Texture

3.6.5.1 General comments Texture is measured on the slabs from the slab compactor with a thickness corresponding to that practiced on the jobsite, and preferentially of dimensions 500 mm x 600 mm.


- 123 -

An average texture depth (ATD) test is performed on the slab, as set forth in the EN 13036-1. As an initial approximation, the following formula can be employed:

ATD (PmT) = ATD (PmT) + 0,3 mm

3.6.5.2 Adjustment to the average texture depth value

Table 40 - Adjustment to average texture depth

Average texture depth (ATD) Less than the targeted value Much lower than the targeted value

Decrease the % fine aggregate by 5 points and increase the > 6 mm proportion

Create a discontinuity and adjust the percentage of fine aggregate

3.6.6 Ancillary tests

3.6.6.1 Percentages of communicating voids (NF P 98-254-2) This test consists of sealing the walls and base of a mix specimen with a known percentage of voids. The quantity of water absorbed by the specimen yields the volume of communicating voids, as expressed in percentage terms compared to the volume of voids; the resulting value generally lies between 16% and 20% for the PA-BBDr material.

3.6.6.2 Cantabre Test (EN 12 697-17) This shock resistance test is practiced on Porous Asphalt mixtures and, above all else, highlights binder consistency properties. Its relevance with respect to behavior under road conditions remains to be demonstrated.

3.6.6.3 Drainage (EN 12697- 18) This test is practiced on drainage mixes as well as stone mastic asphalt (SMA); it takes place at the mixing temperature and is intended to evaluate the loss of mastic during material transport. Two methods may be employed herein: the "basket" method for drainage materials, and the Schellenberg method for SMA.

3.6.6.4 Specimen permeability (EN 12697- 19) This test also applies to drainage mixes. A constant-height water column is placed on a cylindrical specimen and percolates into the specimen for a given period of time, either vertically or horizontally.


- 124 -

3.7 Practitioners' advice

3.7.1 Effect of mix design factors – Summary

Table 41 - Practitioners' advice – Mix refinement [for a given type of mix] – Summary of the effect of mix design factors

Factors / effect Induced effect

Percentage of voids Increase % fine aggregate +++

Rutting risk - -

To decrease Increase discontinuity ++

Rutting risk - -

Increase 10% rounded fine

aggregate ++

Rutting risk - - -

Increase bitumen content +

Rutting risk - -

Water resistance Increase enhancer + -

Increase bitumen content +

Rutting risk -

Increase activated fines +

2/6 fraction

Decrease percentage of voids -

Rutting resistance % fine aggregate + + +

Fatigue, sealant -

To increase Increase angularity + +

Voids -

Lower bitumen content +

Fatigue / water resistance -

Lower bitumen grade +

Top-down cracking -

Increase incorporation of PE + +

Increase special bitumen + +

Stiffness modulus bitumen hardness + +

Top-down cracking -

To increase

binder content + +

(The stiffness modulus first rises, then drops as a function

of binder content.)

Rutting / fatigue -

Increase inclusion of PE +

+++ Very positive effect on the characteristic needing correction

--- Very negative effect on another characteristic

++ Positive effect on the characteristic needing correction

-- Negative effect on another characteristic

+ Medium or weak effect on the characteristic needing correction

- Risk of negative effect on another characteristic


- 125 -

3.7.2 Practical tips for the mix designer During the mix design study, it is possible: to select the order by which the various properties are to be verified, or to provisionally streamline verification methods to save time and reduce material quantities, or to take the liberty to investigate broader variation ranges among the set of mix parameters. Priority must be assigned to achieving the main targeted characteristic, once the compactibility characteristics have been verified. As an example, when devising the AC-EME mix design, the stiffness modulus at 15°C / 10 Hz is to be verified, and should fatigue-related properties be studied, just a single test level at the intended deformation for 106 cycles will be performed. If the result obtained exceeds this life cycle duration, the full panoply of tests may be undertaken. At this stage, the predictive relations involving mechanical characteristics (modulus, fatigue) vs. mix design factors can be introduced to optimize the design more quickly, for subsequent summary verification prior to the full test. In all cases, as the optimization process unfolds, it remains possible to reduce the number of samples (e.g. a single Gyratory Compactor specimen, a single Wheel Tracking Tester specimen, scaled-down version of the ITSR method B test (Duriez test), just one fatigue level). It is entirely feasible to test two different mix design specimens during the same Wheel Tracking test. On the other hand, as regards the final design, the complete battery of tests proves necessary for each one of the specified properties.

LPC Bituminous Mixtures Design Guide - Relationships between laboratory and field résults -

- 127 -

4 RELATIONSHIPS BETWEEN LABORATORY AND FIELD RESULTS Since the French method has been based on specifying characteristics in the laboratory for a given mix, it is still necessary to comprehend the relationships existing between results obtained from a sample prepared in the laboratory and a sample extracted in the field. The consistency of this approach (laboratory evaluation / performance predictions for pavements) was verified for certain data points. The magnitude of economic stakes tied to actual performance obtained from the pavement along with the evolution in production and implementation capacities necessitate however focusing, for shorter-interval periods, on the correspondence between values measured on specimens made in the laboratory and those generated on the jobsite. This verification step was performed during a number of studies conducted on various properties, such as gyratory compactor compactibility, rutting, stiffness modulus and fatigue resistance. The approach adopted in all cases consisted of comparing results from laboratory analysis (ensuring that components tested were actually being used onsite) with results obtained from samples extracted in the field, in including a careful estimation of their variability. As regards rutting properties, the results presented stem from two specific jobsite vs. laboratory comparative studies conducted in France and the United States. For the properties of compactibility with the gyratory compactor, stiffness modulus and fatigue resistance, results were drawn from the LPC research topic: "CH15 : Design of hot asphalt mixes". In this particular study, the mix was prepared in the laboratory by varying the binder content around the design value, which led to an initial set of laboratory results. On worksites, the group of results for a given mix and specific test comprised a large number of sample extractions (> 20). A comparative assessment of these two results has yielded the conclusions laid out in the following sections.

4.1 Percentage of voids measured with the Gyratory Compactor (GC)

4.1.1 Experimental objective

On several worksites, results were collected from: - the preliminary design, carried out prior to initiating the works; - laboratory verification using actual site materials; - site tests, with mix materials being output from the mixing plant, by means of

the "onboard" Gyratory Compactor; and - percentage of voids measurements using a gamma-densitometer by

transmission (or in certain cases using a retro-diffusion gamma-densitometer after calibration).

Compaction conditions at the measurement point locations were also verified. Conditions at the analyzed worksites are summarized in the following table:


- 128 -

Table 42 - Site conditions

Type of mix - Category Site Layer -

thickness Application Type of worksite

AC20-GB - Category 2 Volcanic aggregates

(gabros, rhyolite, rhyolitic tuff)

35/50 bitumen 4,2% ext

1

RN 7

Base 10 cm

(2 layers)

Spreading Full width 8 m Compaction

2 tire - 5 tons/wheel 2 smooth (Dynapac 511)

Major highway worksite Pace: 4000 tons/day

AC20-GB - Category 3 Volcanic aggregates



2

RN 7

Foundation13 cm

Spreading Variable width approx. 4 m Compaction

1 tire - 5 tons/wheel 1 smooth (Dynapac 511)

Small job successfully completed

AC14-GB - Category 3 Microdiorite aggregates 35/50 bitumen 4,2% ext

3

RN 149

Foundation10 cm

(3 layers)

Spreading Width 8 m

Compaction 2 tires - 3 tons/wheel

2 smooth (CC 501)

Medium-sized construction site Pace: 1500 tons/day

AC14-GB - Category 3 Vescular basalt

aggregates 35/50 bitumen 4,2% ext

4

A 89

Foundation9 cm

(2 layers)

Spreading Width 8 m

Compaction 2 tires - 5 tons/wheel

2 vibrating (CB 624)

Highway building site Pace: 2000 tons/day

AC20-EME - Category 2Volcanic aggregates



5

RN 7

Foundation10 cm

(2 layers)

Spreading Width 3,,5 m Compaction

1 tire + 1 smooth variable compaction

Small jobsite with considerable number of project hazards, difficult working environment

AC10-BBSG Microdiorite aggregates 35/50 bitumen 4,8% ext

6

RN 7

Binder course 5 cm

Spreading Full width 10 m Compaction

3 tires - 4 tons/wheel3 smooth (CC 501)

Major highway project Pace: 3000 to 3500 tons/day

Note: The tire compactors used, depending on the type of mix, were ballasted between 3 and 5 tons/wheel. Only the grave-bitume AC-GB from the A89 highway job, recognized as difficult to compact, has been compacted by means of vibration using approximately 6 to 8 passes of a medium-loaded vibrating roller; The other mixes are compacted according to the protocol of the heavy front tire followed by a smooth compactor.

4.1.2 Results For the 0/20 mixes, the criterion selected for the Gyratory Compactor (GC) test is the percentage of voids at 120 gyrations, while for the 0/14 and 0/10 Asphalt Concrete AC-BBSG mixtures this criterion is the percentage of voids at 100 gyrations and 60 gyrations, respectively. The reference value is set as the "design verification", since this criterion seems the most reliable, given that it has been obtained using materials found onsite.


- 129 -

The variability study was conducted on jobsites implementing LCPC's mobile Gyratory Compactor (GC), along with a parallel fabrication control. An example of obtained results is provided in Figure 30 below:

Figure 30: Example of GC variability in the percentage of voids obtained onsite

0,0

2,0

4,0

6,0

8,0

10,0

12,0

P1 P2 P3 P4 P6 P7 P8P10 P12 P14 P16 P17 P18 P19 P21 P22 P24 P25 P26 P28 P30 P32

% v

oids

at 1

20 g

yrat

ions

Bitumen content

% passing the 2-mm sieve

Deviation from thetheoreticalformula

AC20-GB - Class 2 - % of voids at 120 gyrations

% Fines

-0,2 0,2 -0,4 0,1

0,3 0,6 -0,3 1

-2 2 -4 4

Void content byGyratory compaction

Laboratory validationMean value of 32 Gyratory results

Prelim inary type testing

Specific result

The main output relative to the preliminary design, verifications, variability and field results have been compiled in Table 43.


- 130 -

Table 43 - % of void measurements – Comparison of laboratory compactor results (design, verification) with onsite results (Gyratory compactor, bulk density (MVA) measurement using

gamma-densitometry)

Site No. % of voids Number of tests

Average%

Min%

Max%

Spread %

Deviation from the

verification Asphalt concrete for base AC20-GB - Class 2 – RN 7

Preliminary design * *** 10,8 + 3,6

Design verification * *** 7,2 -

Inspection on sizable sample (Autun) * 10 7,4 6,5 9,2 2,7 + 0,2

Mobile Gyratory Compactor * 32 7,4 6,2 9,4 3,2 + 0,2

1

Jobsite ** 148 9 7,3 11,7 4,4 + 1,8

Asphalt concrete for base AC20-GB - Class 3 – RN 7

Preliminary design * *** 7,1 + 2,0

Design verification * *** 5,1 -

Mobile Gyratory Compactor * 8 6,3 4,3 7,7 3,4 + 1,2

2

Jobsite ** 10 6,5 4,7 8,4 3,7 + 1,4

Asphalt concrete for base course AC20-GB 3, 6/10 gap-graded - Class 3 – RN 149

Preliminary design (*) *** 9,9 + 2,0

Design verification (*) *** 7,9 -

Mobile Gyratory Compactor (*) 41 9,1 7,6 10,4 2,8 - 1,2

3

Jobsite (**) 41 8,2 5,6 11,2 4,4 + 0,3

High modulus asphalt concrete for base course AC20 (EME 0/20) - Class 2 – RN 7

Preliminary design (*) *** 3,9 + 1,0

Design verification (*) *** 2,9 -

Mobile Gyratory Compactor (*) 23 3,3 1,8 5,2 3,4 + 0,4

5

Jobsite ** 81 5,5 2,2 10 7,8 + 2,6

Asphalt concrete AC10-BBSG – RN 7

Preliminary design [*] *** 9,4 + 2,6

Design verification Mobile Gyratory Compactor (LCPC) [*]

*** 6,8 -

Design verification Gyratory Compactor (LR Autun) [*]

*** 7,4

6

Mobile Gyratory Compactor [*] 32 7,8 6,2 9,4 3,2 + 1,0


- 131 -

Site No. % of voids Number of tests

Average%

Min%

Max%

Spread %

Deviation from the

verification Jobsite (**) 40 6,5 4,0 8,6 4,6 - 0,3

* Results using the Gyratory Compactor at 120 gyrations, (*) at 100 gyrations, [*] at 60 gyrations

** Inspection using the point gamma-densitometer, (**) Inspection using the back-scattering gamma-densitometer

*** Average of at least 3 repetitions

4.1.3 Comments The Gyratory Compaction test specifications associated with product standards have been met for all laboratory verifications using site components. The results obtained for in situ percentage of void measurements using the gamma-densitometer comply with standard-based specifications (i.e. the average onsite value measured must be comparable with designated thresholds). For the majority of jobsites, the results derived practically all satisfy the limits indicated in the standard. For site no, 5, submitted to execution uncertainties, results show greater dispersion. Deviations between the preliminary design with Gyratory Compactor and the design verification step may appear and to a significant extent (such is the case for AC20-GB for base course , class 2 [binder content > 4,0% (int), stiffness > 9000 MPa, fatigue > 80 µdef] (site no. 1) and class 3 [binder content > 4,4% (int), stiffness > 9000 MPa, fatigue > 90 µdef] (site no. 2): 3,6% and 2,0% deviation), due to the non-representativeness of preliminary design materials and sometimes to a sizable lag between preliminary design and site execution (case of the AC14-GB for base course at site no, 3: 2% deviation, 4-year time differential). For conventional materials and appropriate application conditions, the percentage of voids yielded by the Gyratory compactor test during the verification step with jobsite components provides a satisfactory order-of-magnitude estimation of the percentage of voids found on site, The maximum deviation comes to between -1,2% and +1,4%. In the case of faulty compaction (i.e. site no. 5), the average value controlled using the gamma-densitometer is abnormally high (+ 2% vs. the verification value), with a very wide dispersion (9% spread). The laboratory verification with worksite components and the average site value with the mobile Gyratory lead to the same orders of magnitude, taking into account the test reproducibility. The variability in percentage of void figures measured on construction sites (with the gamma-densitometer) is always greater than that using the mobile Gyratory, since outside of fluctuations specific to the material (as reflected in large part by the Gyratory test), application-related fluctuations are at work (layer thickness, support bearing capacity, and especially compaction energy). In the general case, the averages of these two populations compare closely with one another. Specifications relative to the percentage of voids indicated in the product standards are realistic and, in most instances, well respected.


- 132 -

Provided that aggregate samples are highly representative, which is the case here for the "verification" step, Gyratory tests prove to be effective predictors of average field values. The production process does not exert any impact on the average "percentage of voids" parameter. The production average value is the same as that derived during the laboratory investigation. The production process in fact introduces a variability of +1,5%.

4.2 Large device wheel tracking test

4.2.1 The studies conducted in France The comparative studies performed on the basis of sample preparation protocol (in the laboratory, mixed – i.e. mixing plant production and laboratory compaction, and from mix plate samples extracted on worksites) systematically demonstrate the enhanced rutting resistance of field materials. This deviation however is inconsistent and depends on material sensitivity to rutting. As an initial approximation, the following may be adopted: - a rather close similarity in results, provided the mix design displays decent rutting

resistance (e.g. less than 5% at 30000 cycles): deviation of 1% to 2% lower in favor of the worksite;

- a major deviation in the formula sensitive to rutting (e.g. 10% at 3000 cycles); this difference could reach tenfold in terms of number of cycles, for a given level of permanent deformation, which could (as an illustration) reflect a laboratory rut depth of 10% at 3000 cycles, in comparison with a 10% onsite rut depth after 30000 cycles. Figures 32, 33 and 34 show examples of results obtained during wheel tracking experiments conducted in 1992 on the LCPC-Nantes accelerated test carousel.

Figure 31: LCPC Fatigue Carousel


- 133 -

Figure 32: Results obtained with the Large Device wheel tracking Tester - Study of laboratory rutting

Figure 33: Results obtained with the Large Device wheel tracking Tester - Study of rutting on plant-produced mixes

1

10

100

10 100 1000 10000 100000 Number of cycles

50/70

multigrade 50/70

AC-EME 10/20SBS

1

10

100

100 10000 1000000 Number of cycles

50/70

multigrade 50/70

Hard

SBS% ru

tting

%

frut

ting


- 134 -

Figure 34: Behavior of mixes on the LCPC test carousel, evolution of rut depth submitted to a single large wheel (F = 42,5 kN, V = 40 km/h)

It could be anticipated that producing a plant mix leads to likely evolution through binder aging, potentially associated with a modified bitumen structure (eventually characterized by lower thermal susceptibility of the binder), and thus to improved rutting resistance. Though laboratory rutting behavior offers a more pessimistic view than reality on the worksite, the conclusion of systematically accommodating a higher level of laboratory rutting may not be forwarded. The benchmark for design specifications is based directly on both results determined in the laboratory, according to the laboratory mixing method protocol, and actual behavioral observations made on pavements, depending on the combination of mechanical and thermal loadings. In seeking to determine the resistance to rutting from field sampling, it would be necessary to modify and strengthen specifications in order to account for the discrepancies between laboratory and jobsite that were mentioned above, by recalling that deviations also depend on material sensitivity, which significantly complicates the determination of these new thresholds. Rutting results, when obtained using different sample preparation modes, must never be compared.

4.2.2 Colorado study Towards the beginning of the 1990's, a major study was conducted by the U,S, Federal Highway Agency (FHWA) in the state of Colorado (T, Aschenbrener), intended to assess the pertinence of the LPC large device wheel tracking test as a means for qualifying field behavior. This study consisted of comparing LPC wheel tracking test results (extraction of in situ material plates) to older pavement surfacing with known onsite performance (rut depth measured on the pavement). The origin of material rutting flaws on these test sections had been due to either defective design or construction (poor mix design), thereby making material age, which from a rutting

02468

10 12 14

0 50000 100000 150000 200000Number of loadings

BB Reference BB EM BB SBS


- 135 -

perspective tends to reduce deformation (i.e. binder hardening due to aging). potentially considered as a secondary factor. A total of 31 sites were selected. The comparisons of laboratory and field results have been summarized in the following table:

Table 44 – Comparison between the field behavior of material mixes and the acceptance or rejection criterion according to French specifications

Effective field performance

No rutting Rutting

Results obtained with Good* 4 0

LCPC large device wheel tracking test

Poor* 11 16

NOTE: A good or poor indication with respect to French specifications < 10% at 30,000 cycles and a 60°C test temperature

These results led to the following conclusions (extracted from the study article): - The study has highlighted the capacity of the rut tester to predict pavement behavior; - The correlations of LCPC rut tester results with rutting depth in the field are excellent when temperature is taken into account (based on two levels: laboratory testing at 50°C and 60°C for onsite temperatures of 27-32°C and 32-38°C, respectively) along with site traffic (once again based on two levels: above and below an EDLA value of 400). (The LCPC wheel tracking test on Colorado pavements – T. Aschenbrener – Colorado Department of Transportation, USA – RGRA No, 729 – May 1995) It is recalled that temperature and especially legal load conditions are very different between the United States and France (in terms of axle load: just 80 kN in the U.S. vs. 130 kN in France). Since these parameters exert a strong impact on the resistance to rutting, account should be made of this fact in both test protocols and specification thresholds.

4.2.3 Ranking of mix rutting behavior The ranking of mixes, according to their sensitivity to rutting, remains identical between laboratory and worksite (provided the mix design has been respected). Nonetheless, laboratory testing is a better indicator of deviations among material compositions than data obtained from field samples. The selectivity inherent in laboratory tests, with respect to the rutting criterion, proves highly relevant in terms of in situ behavior and facilitates differentiation across materials, making it possible to study sensitivity and composition optimization factors.


- 136 -

4.3 Stiffness modulus test

4.3.1 Experimental objective and procedure The French mix design method relies on the laboratory determination of various characteristics that allow predicting the in situ performance of bituminous materials, An LPC research project (CH 15: "Design of hot asphalt mixes") was thus undertaken to respond to such questions. This program purposely focused on pavement structure materials (primarily asphalt concrete for base course (AC-GB grave-bitume) and AC-EME high-modulus asphalt concrete mixes) in addressing, to the greatest extent possible, the main categories of materials used in road and highway structures, along with a wide range of aggregate origins. In particular, it was sought to characterize the variations in stiffness modulus obtained in the field. To proceed, some 20 extraction sites were determined in the field, distributed over the entire length of the jobsite (approximately 10 km). At each site, two core samples 150 mm and 300 mm in diameter were produced. The 150 mm samples yielded prismatic specimens for determining the direct tensile modulus, In each of the 300-mm diameter samples, 3 trapezoidal specimens were extracted in order to derive the complex modulus. The identification of 3 individual results at any single point served to estimate local variability. Field values were then compared with laboratory values on materials produced using the worksite formulation and components.

Figure 35: In situ core sampling Figure 36: In situ sawing


- 137 -

4.3.2 Results

4.3.2.1 In situ variability

Two examples of the variability obtained on a AC-GB grave bitume foundation layer are shown in the following figures:

Figure 37: Variability in stiffness modulus on in situ extractions (site no, 1)

Figure 38: Variability in stiffness modulus on in situ extractions (site no, 2)

Mod

ulus

(M

PA

Mod

ulus

(MP

A

Modulus variability at 15°C

10000

11000

12000

13000

14000

15000

16000

17000

0 5 10 15 20 25

MAER prismatic 0,02 sec

|E*| 10 Hz (average 3 samples)

Mod

ulus

(MP

A)

Modulus variability at 15 °C

9000 10000 11000 12000 13000 14000 15000 16000 17000

1 6 11 16 21Sample number

MAER prismatic 0.02 sec

|E*| 10 Hz (average 3 samples

Sample number

Mod

ulus

(MPA

)


- 138 -

The weak level of dispersion should be noted between the 3 complex modulus values measured on the 3 specimens originating from a single coring. The average deviation between the 3 values measured at 15°C / 10 Hz comes to 460 MPa, with all individual deviations lying below 700 MPa (except for a single point, where this deviation reached 1100 MPa). For the two worksites examined herein, out of some twenty extractions performed, a dispersion on the order of 25% to 40% was observed, i.e. a coefficient of variation equal to 5,5% to 9,1%. It should also be pointed out that in both cases, the values measured onsite exceed the specifications for bituminous aggregates. Attention can nonetheless be drawn to the case of site no. 2. where the lowest value obtained randomly (on the order of 9450 MPa for a void content of 9,6%), lies close to the threshold value of the class 3 of grave-bitume, AC-GB3 specification. This value is indeed significant in that the moduli measured on the three specimens stemming from the same core sample display a small deviation of 400 MPa. On the two studied sites the complex modulus at 15°C, 10 Hz and the direct tensile modulus at 15°C, 0,02s are of the same order of magnitude for most of the extraction sites.

4.3.2.2 Worksite - laboratory comparison For both field sites discussed above, the average value of complex moduli measured onsite is situated close to that resulting from the laboratory study. Figure 39 offers a summary of results obtained from all studied sites under investigation and underscores the following elements:

• the main laboratory results (minimum, average and maximum value from among the full set of results: composition variants, various measurement methods);

• the main field results (minimum, average and maximum value from the set of measurement results); and

• for sites not incorporated into any variability study, an estimation of extreme values derived by applying an arbitrary variability of 30%,


- 139 -

Figure 39: Laboratory-worksite correlation: Stiffness modulus at 15°C (0,02 sec or 10 Hz)

The range of field results for a given site was determined simply by taking maximum and minimum values from the entire set of results obtained. It could be observed that the variability in laboratory-measured values was of small magnitude. The laboratory-measured values correspond well with the average field-measured values for sites 1, 4 and 5 and with the minimum values measured on sites 2 and 3. Standards specify minimum stiffness modulus values (at 15°C, 10 Hz or 0,02 sec) measured in the laboratory. These values are then used for designing the pavement structures. For asphalt concrete for base course (AC-GB graves-bitume) [Classes 2 and 3], the minimum value equals 9000 MPa; for AC-EME high-modulus mixes, this value climbs to 14000 MPa. For all 5 sites, the minimum modulus values measured in the field are either greater than or equal to the minimum value specified in laboratory tests. The onsite performance between asphalt concrete for base course AC-GB and high-modulus asphalt concrete mixes, AC-EME turns out to be highly differentiated. It proves impossible, from these results, to detect any "material nature" effect.

Comparison of sets of results

14892

9723

1188112168 12600

19124

117221234612267

14833

20500

13155

1607516246 16639

8000 10000 12000 14000 16000 18000 20000 22000

Labo

rato

ry

Jobs

ite 1

Jobs

ite

Jobs

ite 1

Labo

rato

ry

SIT

E 2

Jobs

ite

SIT

E 2

Labo

rato

ry

SIT

E3

Jobs

ite

SIT

E 3

Ran

ge 3

0%

SITE

3

Labo

rato

ry

SIT

E 4

Jobs

ite

SIT

E4

Ran

ge 3

0%

SIT

E 4

Labo

rato

ry

SIT

E 5

Jobs

ite

SIT

E 5

Ran

ge 3

0%

SIT

E 5

Mini

Ave

Max

Modulus, in MPa

Interval ofworksite

values


- 140 -

4.4 Fatigue test

4.4.1 Experimental objective and procedure Along the same lines as for stiffness modulus values, this CH15 research project on "Design of hot asphalt mixes" focused on the fatigue performance of pavement structure materials (Grave bitume AC-GB and high-modulus mixes AC-EME for the most part) by means of encompassing, to the greatest extent possible, the main categories of materials used in road and highway structures, as well as aggregates of widely-varying origins. Series of large-diameter core samples were extracted on sites featuring asphalt concrete for base course (Graves-bitume) AC-GB and asphalt concrete for surface courses mixes AC-BBSG. These samples yield trapezoidal specimens that allow conducting about ten fatigue tests (protocol calling for a smaller number of replicas), so as to derive an estimation of worksite variability. Only results from the A77 highway site, using a asphalt concrete for base course Class 3 (AC-GB class 3), will be presented here.

4.4.2 Results obtained Figure 40 displays a summary of the fatigue results obtained in accordance with the various sample preparation protocols,

Figure 40: Summary of fatigue test results by sample preparation protocol (preliminary design, laboratory verification, onsite extractions)

The results obtained on this site incite the following comments:

⎯ A small dispersion in mechanical properties:

• average stiffness modulus variation (average of 4 repeated tests per site): 10940 to 13584 MPa (± 10% of average value);

variability of epsilon 6

80

85

90

95

100

105

110

1 2 3 4 5 6 7 8 9 10

avera

ge si

te

prelim

inary

study

labora

tory s

tudy

measurement location

epsi

lon6

(µde

fs)


- 141 -

• the fatigue criterion varies from 91 to 106 µdef (± 7% of average value).

⎯ In conjunction with these findings, it has been observed that placement conditions are very well respected (9 to 10 cm thickness, 3 to 5% void content on tested samples, i.e. 1 or 2 points more in place for the foundation void content).

⎯ A very strong level of correspondence between preliminary design, laboratory verification and average "site" findings. The deviations in both modulus (1300-MPa spread) and fatigue (5-µdef spread) are less than the test tolerance ranges.

⎯ A compensation between modulus values and the fatigue criterion for onsite extractions (in general, as the modulus increases, the fatigue criterion decreases and vice versa).

⎯ A very high level of regularity from fatigue tests on the "site" samples, with test dispersion reflected by the residual standard deviation σx/y being limited (on average 0,48 and a min/max spread of 0,33 to 0,67); this value is to be compared with the laboratory verification result (σx/y = 0,67). These results confirm efficient worksite scheduling, thereby leading to dispersions no greater than those observed on the laboratory preparations.

⎯ As for the asphalt concrete for base course (Grave-bitume) class 3 AC-GB3 standard specifications (modulus of 9000 MPa and fatigue > 90 µdef), the individual results from onsite extractions always exceed these thresholds, especially for modulus value (confirmation from experience gained on modulus measurements). In contrast, the fatigue criterion remains narrowly limited (minimum of 91 µdef).

⎯ It is also to be noted that the percentage of voids lies below the range established in the standard for determining mechanical properties (i.e. 7% to 10% for asphalt concrete for base course (Grave-bitume) class 2, AC-GB2 and class 3, AC-GB3, yet 5% and 10% for a category 4). This asphalt concrete for base course (AC-GB Grave-bitume) category 4, AC-GB4 is the one sought by the highway sector; the target modulus thus stands at 11000 MPa and Epsilon 6 > 100 µdef; these values, on average, are attained yet such is not the case for the minimum fatigue values.


- 142 -

4.5 Synthesis of the relationships between laboratory and field results

The method described in the certified 2nd-generation French standards and thus in EN 13108 series, as presented in this guide's second chapter on "Type testing of asphalt mixtures", has been verified for structural type materials. Results obtained in the laboratory on commonly-used worksite materials comply with requirements laid out in the standards. The consistency of the approach based on laboratory-determined performance has been verified:

1. For percentage of void values measured using the gyratory compactor, which comply with the ranges prescribed in the standards and are representative of measured in situ values, the production process does not introduce any bias;

2. For stiffness modulus measurements, which also comply with standard prescriptions and for which field values are either equal to or greater than laboratory measurements. As regards the modulus values, it should be noted that a single isolated value from a site extraction cannot be generalized for the purpose of bringing into question the pavement design.

3. Concerning fatigue tests, the material studied exhibited performance values below the expected benchmark (AC-GB3 instead of AC-GB4), The correlation between laboratory values and field values is quite good and shows little dispersion.

4. The orders of magnitude for dispersion observed on sites where the current state-of-the-art has been adequately respected are as follows:

• Gyratory Compactor: base course mixtures ± 2 to 2,5 points, surface layer mixtures ± 1 to 1,5 points

• Modulus values: ± 20% to 30% • Fatigue: ± 10% to 15% • Rut depth (large device): approximately 2 points for a mixture

showing little sensitivity to rutting (< 5% at 30000 cycles) 5. The mechanical properties measured on a single coring must

not be selected as a hypothesis in carrying out an inverse design calculation that serves to estimate a new life cycle duration for the project.

The values obtained onsite display an unavoidable level of dispersion. A large number of results must therefore be available in order to generate an actual view of in situ performance. The worksite-laboratory results comparison can only be utilized by incorporating these variability data since study conclusions are capable of changing entirely, depending on whether the value obtained from a single site sample is high or low. For this reason, no conclusion should be forwarded on the basis of a single extraction performed on the worksite.

LPC Bituminous Mixtures Design Guide - Conclusion -

- 143 -

5 CONCLUSION All steps associated with this approach have been preserved in the application of EN standards, including the water-sensitivity in the revised version of the EN standard, which is assessed via a direct compression test. As regards "structural" materials, it is indeed possible to apply a "fundamental" approach, a situation already encountered in today's contracts that implement a rational design process, In contrast, for wearing course mixtures, the approach employed remains highly "empirical" (not just in a EN sense of the term, but as commonly understood as well), The efforts undertaken in refining tests to evaluate surface characteristics of mixes in the laboratory, along with their durability characteristics, must be pursued in order to derive a truly fundamental approach in this field.

LPC Bituminous Mixtures Design Guide - Bibliography - -

- 144 -

Bibliography

Bitumes et enrobés bitumineux – Bulletin de liaison des laboratoires des ponts et chaussées Spécial V– déc. 1977

[Afnor, 2000] - Recueil de normes enrobés hydrocarbonés – AFNOR – 2000 [Afnor, 2000] - Recueil de normes essais relatifs aux chaussées – AFNOR – 2000

[Bonnot, 1993] – Généralités sur les essais mécaniques pratiques de formulation et de contrôle des enrobés bitumineux, Mechanical tests for bituminous mixes – J. BONNOT – Symposium International Rilem, Belgrade, 1983

[Boussad, Dony, 1996] – La rhéologie des liants : un outil pour prédire le module des enrobés- N.BOUSSAD, A.DONY-RGRA n°739 p22

[Boutin,1995] – De la rhéologie du liant à celle de l’enrobé bitumineux, théorie de l’homogénéisation et validation expérimentale – C. BOUTIN, C. DE LA ROCHE, H. DI BENEDETTO, G. RAMOND – Eurobitume workshop, Bruxelles, avril 1995

[Brosseaud, 1993] – Study of permanent deformations in asphalt pavements with the use of the LCPC wheel tracking rutting tester. Evaluation and future prospects –– Y. BROSSEAUD, JL. DELORME, R. HIERNAUX – 72th Annual Meeting TRB, Transportation Research Record, n°1384, p. 59-68 – Washington, 1993

[Ballié, 1990] – Formulation des enrobés – Bilan des essais à la presse à cisaillement giratoire (PCG) – M.BALLIE, JL.DELORME, R.HIERNAUX, F.MOUTIER-; Bulletin de liaison des laboratoires des ponts et chaussées n°170, nov-dec 1990.

[Chappat, Ferraro-Maia, 1997] – Pour y voir plus clair dans les essais SHRP et dans leurs applications aux bitumes polymères – M.CHAPPAT, A.FERRERO-MAÏA - RGRA n° 753 p.52

[Chauvin, 1990] – L’essai de module complexe utilisé pour la formulation des enrobés – JJ. CHAUVIN – Proceedings 4th Rilem Symposium, Budapest, 1990

[Corté et al, 1994] – Investigation f Rutting of Asphalt Surface Layers : Influence of Binder and Axle Loading Configuration– JF. CORTE, Y. BROSSEAUD, JP. SIMONCELLI and G. CAROFF – Transportation Research Record n°1436, 1994

[CRR, 1987] – Code de bonne pratique pour la formulation des enrobés bitumineux – CRR (Centre de Recherche Routière) – Recommandations CRR R69, 1987

[De La Roche, 1996] Module de rigidité et comportement en fatigue des enrobés bitumineux. Expérimentations et nouvelles perspectives d'analyse – C. DE LA ROCHE – nov. 1996


- 145 -

[De La Roche, 1994] – Etude de la fatigue des enrobés bitumineux à l’aide du manège de fatigue LCPC – C. DE LA ROCHE, JF. CORTE, JC. GRAMSAMMER, H. ODEON, L. TIRET, G. CAROFF, – RGRA, n°716, 1994

[De La Roche, 1996] – Module de rigidité et comportement en fatigue des enrobés bitumineux – Expérimentations et nouvelles perspectives d’analyse, thèse de doctorat – C. DE LA ROCHE – Ecole Centrale, Paris, 1996

[De La Roche , 2001] – Essais de fatigue sur les enrobés bitumineux. Résultats de l’expérience d’exactitude – DE LA ROCHE – RGRA n°793, 2001

[Delorme, 1992] Méthode française de formulation des enrobés – JL. DELORME – RGRA hors série – jan. 1992

[Delorme, 2000] – Correspondance entre les caractéristiques mesurées sur des matériaux de laboratoire et sur des matériaux prélevés sur chantier – Module de rigidité – JL. DELORME, L. WENDLING, C. DE LA ROCHE, Y. BROSSEAUD, N. RIVIERE, C. LEROUX – EUROBITUME Barcelone, 2000

[Delorme, 2000] – Correspondance entre les caractéristiques mesurées sur des matériaux de laboratoire et sur des matériaux prélevés sur chantier – Presse à Cisaillement Giratoire – JL. DELORME, L. WENDLING, C. DE LA ROCHE, Y. BROSSEAUD, N. RIVIERE, C. LEROUX – EUROBITUME Barcelone, 2000

[Delorme, 1996] – Les enrobés à module élevé EME) : description, usages, performances – JL. DELORME, V. GOYON, M. GAVALDA – EURASPHALT & EUROBITUME Congress, vol 8, n°196, 1996

[Di Benedetto, Corté, 2005] – Mécanique et ingénierie des matériaux – Matériaux routiers bitumineux 1 – Description et propriétés des constituants – H. DI BENEDETTO, JF. CORTE – Hermes Sciences, 2005

[Di Benedetto, Corté, 2005] – Mécanique et ingénierie des matériaux – Matériaux routiers bitumineux 1 – Constitution et propriétés thermomécaniques des mélanges – H. DI BENEDETTO, JF. CORTE – Hermes Sciences, 2005

[Di Benedetto, De la Roche, 1998] – State of art on stiffness modulus and fatigue of bituminous mixtures – H. DI BENEDETTO, C. DE LA ROCHE, L. FRANKEN – Spon, 1998

[Duriez, 1950] – Traité de matériaux de construction – DURIEZ – éditions Dunod ,1950

[Grimaux, 1979] Vers une nouvelle méthodologie d'étude des enrobés – JP. GRIMAUX – Bulletin de liaison des laboratoires des ponts et chaussées n°10411 – déc. 1979

[Grimaux, Hiernaux, 1977] – Utilisation de l’orniéreur type LPC – JP. GRIMAUX, R. HIERNAUX – Bulletin de Liaison des Laboratoires des Ponts et Chaussées – Special V, LCPC, p. 165-172 – Paris ,1977

[Huet] Rapport LCPC n°14 – M. HUET


- 146 -

[Lesage, 1996] – Quand les propriétés rhéologiques du bitume peuvent-elles servir à prédire avec succès les performances des enrobés – M. LESAGE – EURASPHALT, 1996

[Linder, 1977] – Comportement en traction simple des enrobés hydrocarbonés – R. LINDER – rapport n°72, LCPC Paris, 1977

Mines et carrières – octobre 1996, volume 78

[Moutier, 1990] – Contrôle de qualité des enrobés à l’aide de machine asservie d’essais rhéologiques – F. MOUTIER, JL. DELORME – Proceedings of 4th international Symposium, Budapest, 1990

[Moutier] – Étude statistique de l’effet de la composition des enrobés bitumineux sur leur comportement en fatigue » – F. MOUTIER – Bulletin de liaison des laboratoires des ponts et chaussées n°172 p.40

[Moutier, 1996] – Modélisation des résultats de la PCG – Réflexions à propos du seuil ultime de compactage – F. MOUTIER – Eurobitume Eurasphalt Congress, vol. 4, n°57, Strasbourg, 1996

[Moutier, 1992] – Utilisation de la Presse à Cisaillement Giratoire et de l’orniéreur dans la méthode française de formulation des enrobés bitumineux – F. MOUTIER – Proceedings of 5th Eurobitume congress, vol 1B, Stockholm juin 1992

National Research Council, Strategic Highway Research Program, The superpave mix design manual for new construction and overlays. Report SHRP-A-407, Washington, 1994

[Piau, 1989] – Modélisation thermomécanique du comportement des enrobés bitumineux – JM. PIAU – BL n°163, septembre-octobre 1989

[Rilem, 1998] – Bituminous binder and mixes – Rilem report, n°17, Londres 1998

[SHRP, 1994] - The Superpave mix design – Manual for new construction and overlays – SHRP – 1994

[Soliman, 1976] – Influence des paramètres de formulation sur le comportement à la fatigue d’un enrobé bitumineux – S. SOLIMAN – Rapport de recherche LPC n°58, 1976

[Soliman, 1977] – Influence des paramètres de formulation sur le module et la résistance en fatigue des graves-bitumes – S. SOLIMAN, TH. DOAN – Bulletin de Liaison des Laboratoires des Ponts et Chaussées numéro spécial V, 1977

[Usirf, 2001] - Les enrobés bitumineux Tome 1 – USIRF – RGRA – déc. 2001 [Usirf, 2003] - Les enrobés bitumineux Tome 2 – USIRF – RGRA – déc. 2003

[Van der Poel, 1954] – A general system describing the viscoelastic properties of bitumen and its relation to routine test data – C. VAN DER POEL – J.Appl. Chem, vol 4, n°5, 1954


- 147 -

[William, 1955] – The temperature dependence of relaxation mechanisms in anomorphous polymers and other glasforming liquids – ML. WILLIAM, RF. LANDEL, JD. FERRY – Journal of American Chemistry Society, n°20, 1955

LPC Bituminous Mixtures Design Guide - Appendix A – List of normative references -

- 149 -

Appendix A:

List of normative references required for the type testing phase

1 - Normative references relative to mix components

Standard Title

EN 13043 Aggregates for bituminous mixtures and surface treatments for roads, airfields and other trafficked areas

XP P18-545 Aggregates: Bases for definition, compliance and classification

EN 932-2 Test for general properties of aggregates - Part 2: Methods for reducing laboratory samples

P 18-559 Measurement of sand and gravel mass density in paraffin oil

EN 933-1 Tests for geometrical properties of aggregates - Part 1: Determination of particle size distribution - Sieving method

(NF P 98-256-1)(07/91) Aggregates: Determination of the absorbent power of fines

(For information: This reference is no longer applied in practice.)

EN 932-5 Test for general properties of aggregates - Part 5: Common equipment and calibration

EN 933-3 Tests for geometrical properties of aggregates - Part 3: Determination of particle shape - Flakiness index

EN 933-5 Tests for geometrical properties of aggregates - Part 5: Determination of percentage of crushed and broken surfaces in coarse aggregate particles

EN 933-6 Test for geometrical properties of aggregates - Determination of surface characteristics - Part 6: Flow coefficient of aggregates

EN 933-9 Tests for geometrical properties of aggregates - Part 9: Assessment of fines - methylene blue test

EN 933-10 Test for geometrical properties of aggregates - Part 10: Assessment of fines - Grading of fillers (air jet sieving)


- 150 -

Standard Title

EN 1097-1 Tests for mechanical and physical properties of aggregates - Part 1: Determination of the resistance to wear (micro-Deval)

EN 1097-2 Tests for mechanical and physical properties of aggregates - Part 2: Methods for the determination of resistance to fragmentation (Los Angeles)

EN 1097-4 Tests for mechanical and physical properties of aggregates - Part 4: Determination of the voids of dry compacted filler

EN 1097-7 Tests for mechanical and physical properties of aggregates - Part 7: Determination of the particle density of filler - pycnometer method

EN 1097-8 Tests for mechanical and physical properties of aggregates - Part 8: Determination of the polished stone value

EN 13179-1 Tests for filler aggregate used in bituminous mixtures - Part 1: Delta ring and ball test

ISO 565 Test sieves – Metal wire cloth, perforated metal plates and electroformed sheets – Nominal dimensions of sieve openings

EN 12697-11 Bituminous mixtures – Test methods for hot-mix asphalt – Part 11: Determination of the affinity between aggregate and bitumen

EN 58 Bitumen and bituminous binders - Sampling of bituminous binders

EN 1426 Bitumen and bituminous binders - Determination of needle penetration

EN 1427 Bitumen and bituminous binders - Determination of the softening point - Ring and ball method

EN 12591 Bitumen and bituminous binders - Specifications for paving grade bitumen

EN 12593 Bitumen and bituminous binders - Determination of Fraass breaking point


- 151 -

Standard Title

EN 12594 Bitumen and bituminous binders - Preparation of test samples

EN 12607-1 Bitumen and bituminous binders - Determination of the resistance to hardening under influence of heat and air - Part 1: RTFOT method

EN 12697-1 Bituminous mixtures - Test methods for hot mix asphalt - Part 1: Soluble binder content

EN 12697-3 Bituminous mixtures - Test methods for hot mix asphalt - Part 3: Bitumen recovery: Rotary evaporator

EN 12697-4 Bituminous mixtures - Test methods for hot mix asphalt - Part 4: Bitumen recovery: Fractionating column

EN 13924 Bitumen and bituminous binders – Specifications for hard pavig grade bitumens

EN 14023 Bitumen and bituminous binders – Framework specification for polymer modified bitumens

2 - Normative references relative to mix sample preparation

Standard Title

EN 12697-5 Bituminous mixtures - Test methods for hot mix asphalt - Part 5: Determination of the maximum density

EN 12697-38 Bituminous mixtures - Test methods for hot mix asphalt - Part 38: Common equipment and calibration

EN 12697-35 Bituminous mixtures - Test methods for hot mix asphalt - Part 35: Laboratory mixing

EN 12697-33 Bituminous mixtures - Test methods for hot mix asphalt - Part 33: Specimen prepared by roller compactor

NF P 98-250-3 Pavement-related tests – Preparation of asphalt mixes – Roller compaction – Specimen preparation within an asphalt block

EN 12697-6 Bituminous mixtures - Test methods for hot mix asphalt - Part 6: Determination of bulk density of bituminous specimens by hydrostatic methods

EN 12697-7 Bituminous mixtures - Test methods for hot mix asphalt - Part 7: Determination of bulk density of bituminous specimens by gamma rays


- 152 -

Standard Title

EN 12697-29 Bituminous mixtures - Test method for hot mix asphalt - Part 29: Determination of the dimensions of bituminous specimens

EN ISO 13036-1 Road and airfield surface characteristics - Test methods - Part 1: Measurement of pavement surface macrotexture depth using a volumetric patch technique

3 - Normative references relative to laboratory tests

Standard Title NF P 98-251-1 (to be revised or superseded no later than end of 2007)

Static tests on bituminous mixtures - The Duriez test conducted on hot mix asphalt

EN 12697-12 (see comments in Appendix D)

Bituminous mixtures - Test methods for hot mix asphalt - Part 12: Determination of the water sensitivity of bituminous specimens Method B by compression

EN 12697-30 Bituminous mixtures - Test methods for hot mix asphalt - Part 30: Specimen preparation by impact compactor

EN 12697-34 Bituminous mixtures - Test methods for hot mix asphalt - Part 34: Marshall test

EN 12697-31 Bituminous mixtures - Test methods for hot mix asphalt - Part 31: Specimen preparation by gyratory compactor

EN 12697-10 Bituminous mixtures - Test methods for hot mix asphalt - Part 10: Compactability

EN 12697-22 Bituminous mixtures - Test methods for hot mix asphalt - Part 22: Wheel tracking

EN 12697-26 Bituminous mixtures - Test methods for hot mix asphalt - Part 26: Stiffness

EN 12697-24 Bituminous mixtures - Test methods for hot mix asphalt - Part 24: Resistance to fatigue

EN 12697-17 Bituminous mixtures - Test methods for hot mix asphalt - Part 17: Particle loss of porous asphalt specimens


- 153 -

Standard Title

EN 12697-18 Bituminous mixtures - Test methods for hot mix asphalt - Part 18: Binder drainage test

EN 12697-19 Bituminous mixtures - Test methods for hot mix asphalt - Part 19: specimen permeability

4 - Normative references relative to the methodology

Standard Title XP P 98-135 (to be revised or superseded no later than end of 2007)

Reclaimed asphalt - Classification

NF P 98-149 Asphalt mixes – Terminology – Components and composition of mixtures – Implementation – Products – Techniques and processes

NF P 98-150-1

Hot bituminous mixtures- Constituent materials, type testing, mixing, laying, control

EN 13108-1 Bituminous mixtures – Materials specification – Asphalt concretes

EN 13108-2 Bituminous mixtures – Materials specification – Very thin layer asphalt concretes BBTM

EN 13108-3 Bituminous mixtures – Materials specification – Softasphalt EN 13108-4 Bituminous mixtures – Materials specification – Hot-rolled asphalt

EN 13108-5 Bituminous mixtures – Materials specification – Stone mastic asphalt

EN 13108-7 Bituminous mixtures – Materials specification – Porous asphalts EN 13108-8 Bituminous mixtures – Materials specification – Reclaimed asphalt EN 13108-20 Bituminous mixtures – Materials specification – Type testing

LPC Bituminous Mixtures Design Guide - Appendix B- EN testing standards

- 154 -

Appendix B: EN testing standards - EN 12697 series: "Asphalt mixes"

Use recommendations

European standard Comments Recommendation

EN12697-1 Bituminous mixtures – Test methods for hot mix asphalt – Part 1: Soluble binder content

Replaces XP T 66041. Addresses the "cold extraction" method, the Kumagawa method and the continuous centrifugation methods. Describes asphalt mixes with polymer modified bitumen;

Recommended application; the binder content must be expressed in interior % instead of exterior %.

EN12697-2 Bituminous mixtures – Test methods for hot mix asphalt – Part 2: Determination of particle size distribution

Amounts adapted to aggregate quantities recovered at the time of extraction.

EN 12697-3 Bituminous mixtures – Test methods for hot mix asphalt – Part 3: Bitumen recovery: Rotary evaporator

No French standard exists on this topic. Cited in XP P 98-135.

EN12697-4, Bituminous mixtures – Test methods for hot mix asphalt – Part 4: Bitumen recovery: Fractionating column

No French standard exists on this topic. Cited in XP P 98-135.

EN12697-5, Bituminous mixtures – Test methods for hot mix asphalt – Part 5: Determination of the maximum density

No French standard exists on this topic. Water method for the mixture cited in the gyratory compactor standard. Good level of correlation with maximum density, calculated based on P 18-559, using paraffin oil.

EN12697-6 Bituminous mixtures – Test methods for hot mix asphalt – Part 6: Determination of bulk density of bituminous specimens

Replaces NF P 98-250-6, measured by means of hydrostatic weighing. Specifications on the percentage of voids during type testing based on the gyratory compactor test, not affected by these measurement methods (direct height-based measurement).

Recommended application: Cores: – Method C

for type AC-BB or GB asphalt mixes, EME

– Method D for BBDr asphalt mixes

EN12697-7 Bituminous mixtures – Test methods for hot mix asphalt – Part 7: Determination of bulk density of bituminous specimens by gamma rays

Replaces NF P 98-250-5. Nearly identically written.


- 155 -


EN12697-8 Bituminous mixtures – Test methods for hot mix asphalt – Part 8: Determination of the characteristic air voids content of bituminous specimens

A definition standard, and not a test. For information purposes.

EN12697-9 Bituminous mixtures – Test methods for hot mix asphalt – Part 9: Determination of the reference density

Removed from the European reference

not to be used

EN12697-10 Bituminous mixtures – Test methods for hot mix asphalt – Part 10: Compactability

Interpretation method for a compaction test. Does not correspond to any specifications.

For information purposes.

EN12697-11 Bituminous mixtures – Test methods for hot mix asphalt – Part 11: Determination of the affinity between aggregate and bitumen

Cited in EN 13043. Is not used in the current "asphalt mix" reference.

Not to be used any longer.

EN12697-12 Bituminous mixtures – Test methods for hot mix asphalt – Part 12: Determination of the water sensitivity of bituminous specimens

Method B and preparation of the specimens by compression corresponds to the DURIEZ test NF P 98-251-1

Due to the low precision of the method (given in the standard) and the results of experiment, the method A is not recommended.

EN12697-13 Bituminous mixtures – Test methods for hot mix asphalt – Part 13: Temperature measurement

No corresponding French standard. Recommended application including on the jobsites.

EN12697-14 Bituminous mixtures – Test methods for hot mix asphalt – Part 14: Water content

No corresponding French standard. Recommended application.

EN12697-15 Bituminous mixtures – Test methods for hot mix asphalt – Part 15: Determination of the segregation sensitivity

Unstructured method. For information purposes.

EN12697-16 Bituminous mixtures – Test methods for hot mix asphalt – Part 16: Abrasion by studded tires

Not relevant in France.

EN12697-17 Bituminous mixtures – Test methods for hot mix asphalt – Part 17: Particle loss of porous asphalt specimens

Informational; test conditions need to be specified (temperature in particular).

EN12697-18 Bituminous mixtures – Test methods for hot mix asphalt – Part 18: Binder drainage test

For information purposes. Basket method for PA-BBDr.


- 156 -


EN12697-19 Bituminous mixtures – Test methods for hot mix asphalt – Part 19: Specimen permeability

For information purposes.

EN12697-20 Bituminous mixtures – Test methods for hot mix asphalt – Part 20: Indentation using cube or Marshall specimens

For information purposes, if D ≤ 11 mm

EN12697-21 Bituminous mixtures – Test methods for hot mix asphalt – Part 21: Indentation test using plate specimens

Replaces T 66-002 Recommended application, if D > 11 mm

EN12697-22 Bituminous mixtures – Test methods for hot mix asphalt – Part 22: Wheel tracking test

Replaces NF P 98-253-1 (The standard NF P 98-253-1 has been deleted from the AFNOR reference) Nearly identically written. See position of temperature probes.

Recommended application. Large-device.

EN12697-23 Bituminous mixtures – Test methods for hot mix asphalt – Part 23: Determination of the indirect tensile strength of bituminous specimens

Test cited in EN12697-12 See remark of EN 12697-12.

EN12697-24 Bituminous mixtures – Test methods for hot mix asphalt – Part 24: Resistance to fatigue

Replaces NF P 98-261-1. Identically written.

Appendix A

prEN 12697-25 Bituminous mixtures – Test methods for hot mix asphalt – Part 25: Cyclic compression test

EN12697-26 Bituminous mixtures – Test methods for hot mix asphalt – Part 26: Stiffness

Replaces NF P 98-260-1 and NF P 98-260-2. Broader range of operating conditions.

Application solely under conditions associated with "product" standard specifications (15°C and 10 Hz or 0,02 sec). Extrapolations from other loading times are not considered as valid.

EN12697-27 Bituminous mixtures – Test methods for hot mix asphalt – Part 27: Sampling

No corresponding French standard.

Application

EN12697-28 Bituminous mixtures – Test methods for hot mix asphalt – Part 28: Preparation of samples for determining binder content, water content and grading

No corresponding French standard.

EN12697-29 Bituminous mixtures – Test methods for hot mix asphalt – Part 29: Determination of the dimensions of bituminous specimens

No corresponding French standard. Application.


- 157 -


EN12697-30 Bituminous mixtures – Test methods for hot mix asphalt – Part 30: Specimen preparation by impact compactor

Replaces NF P 98-251-3. New equipment operating protocol.

Informational; with equipment investment, this application is recommended.

EN12697-31 Bituminous mixtures – Test methods for hot mix asphalt – Part 31: Specimen preparation by gyratory compactor

Replaces NF P 98-252. Nearly identically written, except for maximum density by direct measurement according to EN 12697-5, method A in water. Possibility of measuring the internal angle for type compliance.

Application

EN12697-32 Bituminous mixtures – Test methods for hot mix asphalt – Part 32: Laboratory compaction of bituminous mixtures by vibratory compactor

EN12697-33 Bituminous mixtures – Test methods for hot mix asphalt – Part 33: Specimen prepared by roller compactor

Replaces NF P 98-250-2. The replaced standard has been included in the new document; yet other equipment set-ups are also possible.

Recommended application. Device no. 5.1.1

EN12697-34 Bituminous mixtures – Test methods for hot mix asphalt – Part 34: Marshall test

Replaces NF P 98-251-3. New equipment operating protocol.

Informational; with equipment investment, this application is recommended.

EN12697-35 Bituminous mixtures – Test methods for hot mix asphalt – Part 35: Laboratory mixing

Replaces NF P 98-250-1, with a few differences: no overheating even if the mixer is not thermo-regulated. Mixers remain unspecified.

Application

EN12697-36 Bituminous mixtures – Test methods for hot mix asphalt – Part 36: Determination of the thickness of a bituminous pavement


EN12697-37 Bituminous mixtures – Test methods for hot mix asphalt – Part 37: Hot sand test for the adhesivity of binder on pre-coated chippings for HRA (hot-rolled asphalt)

EN12697-38 Bituminous mixtures – Test methods for hot mix asphalt – Part 38: Common equipment and calibration


EN 12697-39 Bituminous mixtures – Test methods for hot mix asphalt – Part 39: Determination of binder content by ignition

Application.

EN 12697-40 Bituminous mixtures – Test methods for hot mix asphalt – Part 40: In situ drainability

Equipment different from NF P 98-254-3. Relationship to be demonstrated.


- 158 -


EN 12697-41 Bituminous mixtures – Test methods for hot mix asphalt – Part 41: Resistance to deicing fluids

Airfields

EN 12697-42 Bituminous mixtures – Test methods for hot mix asphalt – Part 42: Amount of coarse foreign matter in reclaimed asphalt

Application

EN 12697-43 Bituminous mixtures – Test methods for hot mix asphalt – Part 43: Resistance to fuel

Airfields

LPC Bituminous Mixtures Design Guide - Appendix C – Equivalence table between TLext and Bint

- 159 -

Appendix C:

Equivalence table between TLext and Bint

Bint for 2,65 TLext for 2,65 TLext for 2,65 Bint for 2,65 3,50 3,63 3,50 3,38 3,60 3,73 3,60 3,47 3,70 3,84 3,70 3,57 3,80 3,95 3,80 3,66 3,90 4,06 3,90 3,75 4,00 4,17 4,00 3,85 4,10 4,28 4,10 3,94 4,20 4,38 4,20 4,03 4,30 4,49 4,30 4,12 4,40 4,60 4,40 4,21 4,50 4,71 4,50 4,31 4,60 4,82 4,60 4,40 4,70 4,93 4,70 4,49 4,80 5,04 4,80 4,58 4,90 5,15 4,90 4,67 5,00 5,26 5,00 4,76 5,10 5,37 5,10 4,85 5,20 5,49 5,20 4,94 5,30 5,60 5,30 5,03 5,40 5,71 5,40 5,12 5,50 5,82 5,50 5,21 5,60 5,93 5,60 5,30 5,70 6,04 5,70 5,39 5,80 6,16 5,80 5,48 5,90 6,27 5,90 5,57 6,00 6,38 6,00 5,66 6,10 6,50 6,10 5,75 6,20 6,61 6,20 5,84 6,30 6,72 6,30 5,93 6,40 6,84 6,40 6,02 6,50 6,95 6,50 6,10 6,60 7,07 6,60 6,19 6,70 7,18 6,70 6,28 6,80 7,30 6,80 6,37 6,90 7,41 6,90 6,45 7,00 7,53 7,00 6,54 7,10 7,64 7,10 6,63 7,20 7,76 7,20 6,72 7,30 7,87 7,30 6,80

LPC Bituminous Mixtures Design Guide - Appendix D – Main test precisions

- 160 -

Appendix D: Main test precisions

Table 45 – Test repeatability and reproducibility values

Test Measured value Repeatability95% (r)

Reproducibility95% (R) σr σR Observations

ρ 0/2 g/cm3 0,021 0,05 0,0072 0,0194

ρ 2/6 g/cm3 0,013 0,04 0,006 0,014 P 18-559 Maximum density of aggregate in paraffin oil ρ 6/10 g/cm3 0,025 0,035 0,007 0,011

ISO 5725 1996 experiment

EN 12697-5 Determination of maximum density of asphalt mixes

MVR kg/m3 20 45 7,2 16 2005 experiment (provisional results)

Sands 0,56 + 0,017 x(x = average passing % )

0,056 x (x= average passing %)

coarse d, D 3,5 7,7

EN 12697-2 EN 933-1 Determination of particle size distribution by means of sieving Intermediate grades 8 16

EN 12697-33 Specimen preparation by means of roller compaction

Gamma bench compacity (%) 1,09 1992 experiment

NF P 98-251-1 Duriez test Water resistance r/R 0,078 0,134 0,028 0,047 ISO 5725

1998 experiment

NF P 98-251-1 Duriez test

Resistance without immersion, R (MPa) 0,59 2,05 0,21 0,72 ISO 5725

1998 experiment

NF P 98-250-6 Bulk density

Bulk density by means of hydrostatic weighing, % voids

0,67 1,27 0,24 0,45 ISO 5725 1998 experiment

% voids 60 gyrations 0,95 1,38 0,34 0,49

% voids 10 gyrations 0,89 1,53 EN 12697-31 Gyratory compactor

(NF P 98-252) % voids 200 gyrations 1,04 1,57

ISO 5725 1996 experiment

EN 12697-22 Wheel tracking (Large device)

Rutting at 30000 cycles (in mm) 1,11 1,16 0,39 0,41 ISO 5725

1992 experiment

EN 12697-26 Secant modulus

Annex E

Modulus at 0,02 sec, 15°C (MPa)

Average: 15,233 MPa 1,360 2,360 Unpublished

experiment

EN 12697-1 Binder content Binder content 0,27 0,31 0,085 0,121

1995 experiment on the XP T66-041 Standard

EN 12697-1 Binder content All methods combined 0,214 0,348 0,076 0,123 EAPIC

Campaign 1/2003

EN 12697-1 Binder content Cold soluble 0,167 0,225 0,059 0,079 EAPIC

Campaign 1/2003

LPC Bituminous Mixtures Design Guide - Appendix D – Main test precisions

- 161 -

Test Measured value Repeatability95% (r)

Reproducibility95% (R) σr σR Observations

EN 12697-24 Fatigue test Annex A

(NF P 98-261-1) ε

6 (µdef) 4,2 8,3 1,43 2,93 ISO 5725

2000 experiment

EN 12697-26 Complex modulus Annex A

(NF P 98-260-2)

15°, 10Hz (MPa) 335 2,740 118 969 ISO 5725 1999 experiment

EN 12697-7 Gamma bench

(NF P 98-250-5)

Asphalt core sample 2,2942 g/cm3 0,0069 0,0197 0,0024 0,007

ISO 5725 Published in March 2003

Appendix E Summary table – Specifications and recommendations for each type of material

- 162 -

LPC

Bitum

inous Mixtures D

esign Guide

- Appendix E

– Sum

mary table – S

pécifications and recomm

endations

- 163 -

LPC

Bitum

inous Mixtures D

esign Guide

- ooendix E – S

umm

ary table – Spécifications ans recom

mandations

LPC Bituminous Mixtures Design Guide - Appendix F – Product family description

- 164 -

APPENDIX F Product family description

AC-BBSG Asphalt Concrete – Béton Bitumineux Semi-Grenu

Definition Bituminous mixture in accordance with EN 13108-1 characterized by a high coarse aggregate content and designed to yield surface or binder courses with a

thickness of 5 cm or greater until 9 cm. Classification by the resistance to permanent deformation.

Identification AC10-BBSG or AC14-BBSG according EN 13108-1 Surface or binder course

Empirical approach Designation AC10-BBSG0 or AC14-BBSG0

AC10-BBSG1 or AC14-BBSG1 AC10-BBSG2 or AC14-BBSG2 AC10-BBSG3 or AC14-BBSG3

Main characteristics Fragmentation, Wear, Polishing resistance

A20 or LA25, MDE15 or MDE20, PSV 50

Surface course Angularity Coarse; Fine aggregate

C 95/1

ECS 35 Binder course Fragmentation

Wear LA30, MDE25

Coarse aggregate

Grading requirement Flakiness Fine content

GC85/20 or G25/15 ;FI25 ;f2

Fine aggregate or All-in

Grading requirement Methylene blue value

GF85 ; GTC10 ; GA85 MBF10

Usual aggregate

characteristics (minimal values)

Added Filler Stiffness by ring and ball, Void of dry compacted filler

∆R&B 8/16 ; V28/38

Type of binder

Paving grade bitumen 50/70 or 35/50

Minimum binder content AC10 : Bmin5,2 AC14 : Bmin5,0 0,063 5 to 8 0,250 10 to 25 2,0 28 to 38 6,3 50 to 65

Grading : % Sieve in mm

D 90 to 100 Water sensitivity Method B (I/C) ITSR70

AC10 60 gyrations Vmin5 Vmax10 Gyratory AC14 80 gyrations Vmin4 Vmax9

Classification AC-

BBSG 0

AC-BBSG

1

AC-BBSG

2

AC-BBSG

3 Gyratory 10 gyrations V10Gmin11 Not applicable

Nb of cycles 30000 Wheel tracking test

Large device 60°C

Void content of slab {Vi= 5% Vs = 8%}

No perf. determined P10 P7,5 P5

Lev

el 0

Lev

el 1

Lev

el 2


- 165 -

AC-BBME Asphalt Concrete – Béton Bitumineux à Module Élevé Definition Bituminous mixture in accordance with EN 13108-1 whose stiffness is higher

than that of a BBSG mixture and designed to yield surface or binder courses with a thickness of 5 cm or greater until 9 cm.

Classification by the resistance to permanent deformation and by the stiffness. Identification AC10 or AC14 according EN 13108-1

Surface or binder course Fundamental approach

Designation BBME class 1 0/10 or 0/14 BBME class 2 0/10 or 0/14 BBME class 3 0/10 or 0/14


LA25, MDE15, PSV 50

Surface course Angularity

Coarse; Fine aggregate

C 95/1

ECS 35

Binder course

Fragmentation Wear

LA30, MDE25

Coarse aggregate


GC85/20 or G25/15 ;FI25 ;f2




Usual aggregate characteristics

(minimal values)


∆R&B 8/16 ; V28/38

Water sensitivity Method B (I/C) ITSR80 AC10 60 gyrations Vmin5 Vmax10 Gyratory AC14 80 gyrations Vmin4 Vmax9

Classification BBME class 1

BBME class 2

BBME class 3

Nb of cycles 30000 Wheel tracking test Large device

60°C


P10 P7,5 P5

15°C, 10 Hz or 0,02 s Stiffness Void content of slab

{Vi= 5% Vs = 8%} Smin9000 Smin11000

Smin11000

2 points, 10°C, 25 Hz Fatigue Void content of slab

{Vi= 5% Vs = 8%} ε6-100 ε6-100 ε6-100

Leve

l 3

Lev

el 4


- 166 -

AC-BBS Asphalt Concrete – Béton Bitumineux pour chaussée Souple à faible trafic

Definition Bituminous mixture in accordance with EN 13108-1 designed to yield

surface or binder courses for flexible pavement supporting low traffic loads.

Classification by the resistance to permanent deformation. Identification AC10 or AC14 according EN 13108-1

Surface or binder course Empirical approach

Designation AC10-BBS1 AC10-BBS2 AC14-BBS3 AC14-BBS4


LA25, MDE20, PSV 50

Surface course

Angularity Coarse; Fine aggregate

C 50/10 ECS 30

Binder course

Fragmentation Wear

LA30, MDE25 C 50/10 ECS 30

Coarse aggregate


GC85/20 or G25/15 ;FI25 ;f2


Grading requirement Methylen blue value


Usual aggregate



∆R&B 8/16 ; V28/38

Type of binder Paving grade bitumen 50/70 AC10-BBS1

AC10-BBS2

AC14-BBS3

AC14-BBS4 Minimum binder content

Bmin5,2 Bmin4,8 0,063 5 to 8 0,250 10 to 25 2,0 28 to 38 6,3 50 to 65


D 90 to 100 AC10-BBS1

AC10-BBS2

AC14-BBS3

AC14-BBS4 Water sensitivity Method B (I/C)

ITSR80 ITSR80 ITSR80 ITSR70 AC10-BBS1 40 gyrations Gyratory AC10-BBS2 60 gyrations

AC14-BBS3 80 gyrations AC14-BBS4 100 gyrations

Vmin4 Vmax9

Leve

l1

Leve

l 0


- 167 -

AC-BBM Asphalt Concrete – Béton Bitumineux Mince

Definition Bituminous mixture in accordance with EN 13108-1 characterized by an average application thickness of between 3 cm and 5 cm. The material is designed to yield surface courses and possibly binder courses. The particle size distribution is most often gap-graded. Categories A, B, C

depend on the “gap” of the grading curve. Classification by the resistance to permanent deformation.

Identification AC10 or AC14 according EN 13108-1 Surface or (binder) course

Empirical approach Designation AC-BBMA, AC-BBMB or AC-BBMC class 0

AC-BBMA, AC-BBMB or AC-BBMC class 1 AC-BBMA, AC-BBMB or AC-BBMC class 2 AC-BBMA, AC-BBMB or AC-BBMC class 3


LA20 or LA25, MDE15 or MDE20, PSV 50

Surface course


C 95/1

ECS 35 Coarse aggregate


GC85/20 or G25/15 ;FI25 ;f2




Usual aggregate


Added Filler

Stiffness by ring and ball, Void of dry compacted filler

∆R&B 8/16 ; V28/38

Paving grade bitumen 50/70 or 35/50 Type of binder Polymer modified Bitumen 45/80-60 or 40/100-65 Minimum binder content Bmin5,0

0,063 5 to 8 0,250 10 to 23 2,0 27 to 37 4,0 6,3 30 to 40



Category of AC-BBM AC-BBMA AC-BBMB AC-BBMC

Gyratory

40 gyrations Vmin6 Vmax11 Vmin7 Vmax12 Vmin8 Vmax13

Classification AC- BBM 0

AC-BBM 1

AC-BBM 2

AC- BBM 3

Gyratory 10 gyrations V10Gmin11 Not applicable 3 000 cycles P15

10 000 cycles P15 Nb of cycles

30 000 cycles P10 AC-BBMA {Vi= 7% Vs = 10%}

Wheel tracking test

Large device 60°C

Void content of slab

AC-BBMB or

C

No perf. determined

{Vi= 8% Vs = 11%}

Leve

l 0

Leve

l 1

Leve

l 2


- 168 -

AC-BBAC- Asphalt Concrete – Béton Bitumineux Aéronautique (Continu)

Definition Bituminous mixture in accordance with EN 13108-1 designed to yield surface courses and binder courses of airfield pavements. The particle

size distribution is continuous (category C). Classification by the resistance to permanent deformation.

Identification AC10 or AC14 according EN 13108-1 Surface or binder course

Empirical approach Designation BBAC class 0

BBAC class 1 BBAC class 2 BBAC class 3



Surface course


C 95/1

ECS 35 Binder course

Fragmentation Wear

LA30, MDE25

Coarse aggregate


GC85/20 or G25/15 ;FI25 ;f2




Usual aggregate


Added Filler


∆R&B 8/16 ; V28/38

Paving grade bitumen 50/70 or 35/50 Type of binder Polymer modified Bitumen 45/80-60 or 40/100-65 Minimum binder content AC10: Bmin5,4 AC14: Bmin5,2

BBA Surface course

BBA Binder course

0,063 6 to 9 5 to 8 0,250 10 to 25 2,0 35 to 45 32 to 42 6,3 65 to 80 62 to 67


D 90 to 100 Water sensitivity Method B (I/C) ITSR80 TSR70

AC10 60 gyrations Gyratory AC14 80 gyrations Vmin3 Vmax7 Vmin4 Vmax8

Classification BBA class 0

BBA class 1

BBA class 2

BBA class 3

Gyratory 10 gyrations V10Gmi

n11 Not applicable

10 000 cycles Wheel tracking test Large device

60°C


No perf. determi

ned P15 P10 P7,5

Leve

l 0

Leve

l 1

Leve

l 2


- 169 -

AC-BBAD- Asphalt Concrete – Béton Bitumineux Aéronautique (Discontinu)

Definition Bituminous mixture in accordance with EN 13108-1 designed to yield surface and binder courses of airfield pavements. The particle size

distribution is gap-graded (category D), fraction 2/6 or 4/6 is missing Classification by the resistance to permanent deformation.

Identification AC10 or AC14 according EN 13108-1 Surface or binder course

Empirical approach Designation BBAC class 0

BBAC class 1 BBAC class 2 BBAC class 3



Surface course


C 95/1

ECS 35 Binder course

Fragmentation Wear

LA30, MDE25

Coarse aggregate


GC85/20 or G25/15 ;FI25 ;f2




Usual aggregate


Added Filler


∆R&B 8/16 ; V28/38

Paving grade bitumen 50/70 or 35/50 Type of binder Polymer modified Bitumen 45/80-60 or 40/100-65 Minimum binder content AC10: Bmin5,2 AC14: Bmin5,0

0,063 6 to 9 0,250 10 to 25 2,0 35 to 45 4,0 47 to 57 6,3 63 to 73


D 90 to 100 Surface course Binder course Water sensitivity Method B (I/C)

ITSR80 TSR70 Gyratory 40 gyrations Vmin5 Vmax9

Classification BBA D class 0

BBAD class 1

BBA D class 2

BBA D class 3

Gyratory 10 gyrations V10Gmin11 Not applicable 10 000 cycles Wheel tracking

test Large device

60°C Void content of slab {Vi= 4% Vs = 7%}

No perf. determined P15 P10 P7,5

Leve

l 0

Leve

l 1

Leve

l 2


- 170 -

BBTM Béton Bitumineux Très Mince (Very Thin layer Asphalt Concrete)

Definition Bituminous mixture in accordance with EN 13108-2 to be used for surface courses with a thickness of 2cm to 3 cm. The particle size

distribution is most often gap-graded. Classification A, B or D by the void content using gyratory compaction.

Identification Designation

BBTM6A or BBTM10D according EN 13108-2 BBTM6B or BBTM10B according EN 13108-2

Surface course Empirical approach


LA20, MDE15, PSV 50



C 95/1



GC85/15 or G20/15 ;FI30 ;f2



GF85 ; GTC10 ; GA85 or GA90 MBF10

Usual aggregate


Added Filler


∆R&B 8/16 ; V28/38

Paving grade bitumen 50/70 or 35/50 ype of binder Polymer modified

Bitumen 45/80-60 or 40/100-65

Minimum binder content Bmin5,0

BBTM6A BBTM6B BBTM10D BBTM10B

0,063 7 to 9 4 to 6 4,5 to 6,5 4 to 6 0,250 15 to 25 10 to 20 15 to 25 10 to 20 2,0 25 to 35 15 to 25 27 to 33 15 to 25 4,0 25 to 35 20 to 30 6,3 28 to 43 26 to 41


D 90 to 100 90 to 100 Water sensitivity Method B (I/C) ITSR90

Category of BBTM BBTM6A BBTM6B BBTM10D BBTM10BGyratory 25 gyrations Vg 10 to 17 Vg 18 to 25 Vg 10 to 17 Vg 18 to 25 3 000 cycles Mechanical

stability Large device

60°C

Thickness : 50 mm Void content of slab {Vi= 11% Vs = 14%}

P15

Leve

l 0

Leve

l 1

Leve

l 2


- 171 -

PA-BBDr Porous asphalt – Béton Bitumineux Drainant

Definition Bituminous mixture in accordance with EN 13108-7, with bitumen, prepared so as to have a very high content of interconnected voids

which allow passage of water and air in order to provide the compacted mixture with drain and noise reducing characteristics. This material is to

be used for surface courses with a thickness of 3 cm to 4 cm for PA6 and 4 cm to 5 cm for PA10.

Classification BBDr type 1 or BBDr type 2 by the void content using gyratory compaction.

Identification Designation

PA6-BBDr1 or PA6-BBDr2 according EN 13108-7 PA10-BBDr1 or PA10-BBDr2 according EN 13108-7

Surface course Empirical approach


LA20, MDE15, PSV 50



C 95/1



GC85/15 or G20/15 ;FI30 ;f2



GF85 ; GTC10 ; GA85 or GA90 MBF10

Usual aggregate


Added Filler


∆R&B 8/16 ; V28/38

Paving grade bitumen 50/70 or 35/50 Type of binder Polymer modified Bitumen 45/80-60 or 40/100-65 Minimum binder content Bmin4,0

PA6-BBDr1

PA6-BBDr2

PA10-BBDr1

PA10-BBDr2

0,063 [2-10] 4 to 6 2 to 6 4 to 6 2 to 6 0,250 6 to 12 10 to 20 6 to 12 10 to

20 2,0 [5-25] 10 to 15 5 to 12 10 to 15 5 to

12 4,0 15 to 35 12 to 22 6,3 15 to 35 12 to

22


D 90 to 100 90 to 100 Water sensitivity Method B (I/C) ITSR80

Category of PA-BBDr PA6-BBDr1

PA6-BBDr2

PA10-BBDr1

PA10-BBDr2

40 gyrations Vmin20 Vmax26

Vmin26 Vmax30

Vmin20 Vmax26

Vmin26 Vmax30

Gyratory

200 gyrations Vmin16 Vmin20 Vmin16 Vmin20

Leve

l0

Leve

l 1


- 172 -

AC-GB Asphalt Concrete - Grave-Bitume Empirical


lower and upper base courses with a thickness between 8 cm and16 cm.

Classification by binder content. Identification AC14-GB1 or AC20-GB1 according EN 13108-1

AC14-GB2 or AC20-GB2 according EN 13108-1 AC14-GB3 or AC20-GB3 according EN 13108-1 AC14-GB3 or AC20-GB3 according EN 13108-1

Lower or upper base course Empirical approach

Main characteristics Fragmentation, Wear,

LA30, MDE25 Upper base course

Angularity (If wheel tracking test not required) Coarse; Fine aggregate

C 95/1

ECS 35

Lower base course

Fragmentation Wear

LA40, MDE35

Coarse aggregate


GC85/20 or G25/15 ;FI25 ;f2




Usual aggregate


Added Filler


∆R&B 8/16 ; V28/38

Type of binder Paving grade bitumen 35/50 or (50/70) Classification (AC-GB1) AC-GB2 AC-GB3

Minimum binder content (Bmin3,4) Bmin3,8 Bmin4,2 0,063 5 to 8 0,250 10 to 25 2,0 28 to 38 6,3 50 to 65



AC14-GB 100 gyrations AC20-GB 120 gyrations Vmax11 Vmax10

Gyratory 10 gyrations V10Gmin11 10000 cycles

AC-GB2 : {Vi= 8% Vs = 11%}

Wheel tracking test

Large device 60°C

Void content of slab

AC-GB3 : {Vi= 7% Vs = 10%}

No perf. determined

P10

AC-GB Asphalt Concrete - Grave-Bitume Fundamental

Leve

l 0

Leve

l 1

Leve

l 2


- 173 -


lower and upper base courses with a thickness between 8 cm and16 cm.

Classification by stiffness and Fatigue resistance. Identification AC14-GB2 or AC20-GB2 according EN 13108-1

AC14-GB3 or AC20-GB3 according EN 13108-1 AC14-GB4 or AC20-GB4 according EN 13108-1

Lower or upper base course Fundamental approach

Main characteristics Upper base course

Fragmentation, Wear,

LA30, MDE25

Lower base course

Fragmentation Wear

LA40, MDE35

Coarse aggregate


GC85/20 or G25/15 ;FI25 ;f2




Usual aggregate


Added Filler


∆R&B 8/16 ; V28/38

Classification AC-GB2 AC-GB3 AC-GB4 Water sensitivity Method B (I/C) ITSR70

AC14-GB 100 gyrations Gyratory AC20-GB 120 gyrations Vmax11 Vmax10 Vmax9

Void content of the slab:

{Vi= 8%

Vs = 11%}

{Vi= 7% Vs = 10%}

{Vi= 5% Vs = 8%}

Number of cycles 10000 30000

Wheel tracking test

Large device 60°C

Category of rut depth P10

AC-GB2 AC-GB3 AC-GB4 Void content of the slabs ↓ {Vi= 7%

Vs = 10%} {Vi= 5%

Vs = 8%}

Stiffness

15°C, 10 Hz or 0,02 s

Smin9000 Smin9000

Smin11000

Fatigue 2 points, 10°C, 25 Hz ε6-80 ε 6-90

ε 6-100

Lev

el 3

Leve

l 4


- 174 -

AC-EME Asphalt Concrete – Enrobé à Module Élevé

(High-Modulus Asphalt Concrete)

Definition Bituminous mixture in accordance with EN 13108-1 designed to yield lower and upper base courses with a thickness between 6 cm and 8 cm for AC10-EME, between 7cm to 13 cm for AC14-EME and between 9 cm and 15 cm for AC20-EME. High stiffness and fatigue resistance

allow thickness reduction for the pavements. Classification EME1 or EME2 by Fatigue resistance.

Identification AC10-EME1 or AC10-EME2 according EN 13108-1 AC14-EME1 or AC14-EME2 according EN 13108-1 AC20-EME1 or AC20-EME2 according EN 13108-1

Lower or upper base course Fundamental approach

Main characteristics Upper base course

Fragmentation, Wear,

LA30, MDE25

Lower base course

Fragmentation Wear

LA40, MDE35

Coarse aggregate


GC85/20 or G25/15 ;FI25 ;f2




Usual aggregate


Added Filler


∆R&B 8/16 ; V28/38

Classification AC-EME1 AC-EME2 Water sensitivity Method B (I/C) ITSR70

AC10-EME 80 gyr. AC14-EME 100 gyr. Gyratory AC20-EME 120 gyr.

Vmax10

Vmax6

AC-EME1 AC-EME2 Void content of the slabs ↓ {Vi= 7%

Vs = 10%} {Vi= 3%

Vs = 6%} Number of cycles 30000 30000 Wheel tracking

test Large device

60°C Category of rut depth P7,5

Stiffness

15°C, 10 Hz or 0,02 s

Smin14000

Fatigue 2 points, 10°C, 25 Hz ε 6-100

ε 6-130

Lev

el 3

Leve

l4

LPC Bituminous Mixtures Design Guide – Appendix G - Glossary –

- 175 -

Appendix G Glossary

Term Sy

mbo

l or

Abb

revi

atio

n Uni

t

Definition Comments

Added filler Filler of a mineral origin that has been produced separately. EN 13043

Additive Organic or mineral constituent, introduced in small quantities (e.g. organic or inorganic fibers or polymers), intended to modify the mechanical characteristics, workability or color of mixtures.

EN 13108 series

Additive Organic or mineral compound intended to modify the physical or mechanical characteristics of asphalt mixes.

NF P 98-149

Additive content (besides adhesion agents)

% ext. Mass of additive as a ratio of the mass of dry aggregates.

NF P 98-149

Additive content (besides adhesion agents)

% int. Mass of additive as a ratio of the mixture mass.

Adhesion agent Anti-stripping agent

Surface active additive that serves to improve binder-aggregate adhesion.

NF P 98-149

Adhesion agent content

% Enhancing agent mass, as a ratio of binder mass.

Adhesion agent content

% Mass of enhancing agent as a ratio of the binder mass.

Aggregate Granular material used in construction applications. An aggregate may be natural, manufactured or recycled.

EN 13043

Agrochemical binder

A binder derived from vegetal matter without any petrochemical byproduct material.

Air void content v % See Percentage of voids EN 12697-8


- 176 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Air-slaked lime Product derived through a curing process using a very pure limestone.

NF P 98-101

All-in aggregate An aggregate consisting of a mixture of coarse and fine aggregates; it can be produced without separating into coarse and fine aggregates or by combining coarse and fine aggregates. For bituminous mixtures 0/4, 0/6 may be usually used.

EN 13043

Angularity

Characteristic of aggregates with respect to the edges present on each grain.

Angularity of coarse aggregates

C100/0 C95/1 C90/1 C50/10 C50/30 CDeclared

Characteristic of aggregates with respect to the edges present on each grain. According to EN 13043, angularity is characterized for coarser alluvial or marine aggregates by completely-crushed or semi-crushed grain categories, along with fully-rounded grains.

Coarse aggregates derived from solid rock lie in category C100/0

Angularity of fine aggregates

ECS38 ECS35 ECS30 ECSDeclared

According to EN 13043, angularity is characterized for fine aggregates by flow time categories.

Angularity (former standard)

Angularity had been evaluated by either the crushing index (CI) or the crushing ratio (CR) (former standard XP P18-540).

These measures are no longer standardized, yet still do appear in bibliographies.

Angularity

(former standard) Crushing ratio

RC - Ratio between the smallest dimension of the original coarse aggregate submitted to the initial crushing and the D value of the resultant aggregate.


Angularity

(former French standard)

Crushing index

IC % Percentage of elements in excess of D of the resultant aggregate contained in the original material submitted to crushing.


Asphalt concrete for airfield pavements

AC-BBA

Asphalt concrete for airfield pavements (continuous grading curve AC-BBA C or gap-graded grading curve AC-BBA D), in accordance with EN 13108-1.

EB-BBA in the NF EN version


- 177 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Asphalt concrete for flexible pavements supporting light traffic loads

AC-BBS

Asphalt concrete for flexible pavements supporting light traffic loads, in accordance with EN 13108-1.

EB-BBS in the NF EN version

Asphalt Concrete- Grave Bitume

AC-GB

Bituminous mixture in accordance with EN 13108-1 designed to yield lower and upper base courses with a thickness between 8 cm and 16 cm. Fundamental or empirical approach

EB-GB in the NF EN version

Asphalt Concrete- Enrobé à Module Élevé

AC-EME

Bituminous mixture in accordance with EN 13108-1 designed to yield lower and upper base courses with a thickness between 6 cm and 8 cm for AC10-EME, between 7cm to 13 cm for AC14-EME and between 9 cm and 15 cm for AC20-EME. High stiffness and fatigue resistance allow thickness reduction for the pavements.

EB-EME in the NF EN version

Asphalt Concrete-Béton Bitumineux Semi-Grenu

AC-BBSG

Bituminous mixture in accordance with EN 13108-1 characterized by a high coarse aggregate content and designed to yield surface or binder courses with a thickness of 5 cm or greater until 9 cm. Classification by the resistance to permanent deformation.

EB-BBSG in the NF EN version

Asphalt Concrete-Béton Bitumineux Mince

AC-BBM

Bituminous mixture in accordance with EN 13108-1 characterized by an average application thickness of between 3 cm and 5 cm. The material is designed to yield surface courses and possibly binder courses. The particle size distribution is most often gap-graded. Categories A, B, C depend on the “gap” of the grading curve.Classification by the resistance to permanent deformation.

EB-BBM in the NF EN version

Asphalt Concrete-Béton Bitumineux à Module Élevé

AC-BBME

Bituminous mixture in accordance with EN 13108-1 whose stiffness is higher than that of a BBSG mixture and designed to yield surface or binder courses with a thickness of 5 cm or greater until 9 cm.

EB-BBME in the NF EN version

Asphalt limestone

A sedimentary rock impregnated onsite by naturally-occurring bitumen.


- 178 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Average Texture Depth

ATD

Pmt

mm

mm

Measurement of texture using depth “Sand patch” method according

French transcription of ATD

EN 13036-1

Base series + series 1

mm Series of sieves containing the following d or D dimensions: 0, 1, 2, 4, 5.6, 8, 11.2, 16, 22.4, 31.5, 45, and 63.

EN 13043

Base series + series 2

mm Series of sieves containing the following d or D dimensions: 0, 1, 2, 4, 6.3, 8, 10, 12.5, 14, 16, 20, 31.5, 40, and 63.

EN 13043

It is common to use this series for French bituminous mixtures.

Binder course

Part of pavement between the surface course and the base

EN 13108 series

Bitumen A highly viscous or almost solid material, which remains nearly non-volatile, adhesive and water repellent; it is derived from crude oil or present in the form of natural bitumen, which is entirely or almost entirely soluble in toluene.

EN 12597

Bituminous mastic

A mixture of filler and a bituminous binder.

Bituminous mortar

Mixture of fine aggregate 0/2 or all-in 0/4 and a bituminous binder.

Bulk density ρbdimMVa

ρbsea

MVA

ρbγ

g/cm3

or kg/m3

g/cm3

or kg/m3

g/cm3

or

Ratio of the mass of a test specimen to the specimen volume. The volume may be measured by means of geometric methods ρbdim [bulk by dimension] , in which case MVa is obtained, or by hydrostatic methods ρbsea [Bulk sealed ](EN 12697-6) yielding MVA.

In the laboratory, the bulk density is measured in some cases on the gamma

EN Standard

ρbsea (Bulk sealed)

ρbdim (Bulk by dimension)

ρbγ

(Bulk gamma)


- 179 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

MVaγ

or kg/m3

measured in some cases on the gamma densitometer bench (EN 12697-7), which yields ρbγ or MVaγ.

Calculated maximum density

MVRc g/cm3

or kg/m3

MVR, obtained by means of calculation based on the mass densities of the individual components.

ρmc

(maximal calculated)

Cement Hydraulic binder composed of finely-molded inorganic matter which, once mixed with water, forms a paste that sets and hardens subsequent to hydration reaction and process and which after hardening retains both its strength and stability even underwater.

Coarse aggregate

Designation given to the larger aggregate size which D is less than or equal to 45 mm and d greater than or equal to 2 mm.

EN 13043

Coated chippings

Coarse aggregate with a tight granular distribution designed to be embedded into a support matrix of an asphalt layer (NF P 98-133).

Nominally single size aggregate particles with a high resistance to polishing, which are coated with high viscosity binder. The chippings are always rolled into and form a part of hot rolled asphalt surface course.

EN 13108-4

Compacity C % Ratio of the test specimen volume in excluding voids to the total specimen volume.

Complementary test

Test added to the testing program for the particular level. This complementary assessment may be chosen from a higher test level or consist of a test related to a specific technique or for a specific


- 180 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

purpose.

Compressive strength after immersion

I MPa Compressive strength following immersion, as per EN 12697-12 Method B (corresponding to Duriez test (NF P 98-251-1)).

In the Duriez test the compression strength after immersion was expressed as “r”

Compressive strength without immersion

C MPa Compressive strength without immersion, as per EN 12697-12 Method B (corresponding to Duriez test (NF P 98-251-1)).

In the Duriez test the compression strength without immersion was expressed as “R”

Connecting voids

Voids in a test specimen that enable a fluid to cross from one face to the other.

Content of additives (excluding adhesion agents)

% ext. Mass of additives as a ratio of the dry aggregate mass.

NF P 98-149

Content of additives (excluding adhesion agents)

% int. Mass of additive as a ratio of the mixture mass.

Conventional specific surface area

Σ m2/kg Determined by the following relation:

100 Σ = 0,25 G + 2,3 S + 12 s + 150 f, with:

G proportion of elements larger than 6,3 mm,

S proportion of elements lying between 6,3 mm and 0,250 mm in size,

s proportion of elements between 0,250 mm and 0,063 mm

f proportion of elements smaller than 0,063 mm

This calculation is not applicable when the mixture contains either special fillers or additives, such as fibers.

Correction coefficient for binder content

α Mg/m3 α = 2,650 / ρd where ρ

d is the mean particle

density of aggregate, in Mg/m3, determined according to EN 1097-6.

EN 13108 series Several methods are described in EN 1097-6. ρ

d

should be


- 181 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

interpreted

Course

Structural element of a pavement constructed with a single material. A course may be laid in one or more layers.

EN 13108 series

Crushing index IC % Percentage of elements larger than D in the resultant aggregate contained in the original material submitted to crushing.

Former definition. See angularity.

Crushing ratio RC - Ratio of the smallest dimension in the original coarse aggregate, submitted to the initial crushing, to the D value of the resultant aggregate.

Definition corresponding to a standard since rescinded, yet still used in bibliographical references. See angularity.

Delta ring and ball temperature

∆R&B

∆TBA

°C Stiffening power of a filler, as measured by the difference in ring and ball temperature obtained on a bitumen and mastic composed by the tested filler and bitumen, as per Standard EN 13179-1.

∆TBA is the French transcription of ∆R&B

EN 13043

Typical values: ∆R&B 8/16 ∆R&B 8/25

Dry filler porosity

See description under Rigden Voids Index.

Dynamic modulus

E(θ, f) MPa Standard for the complex modulus, expressed in MPa, as obtained at a temperature θ in °C and for a frequency f in Hz (EN Standard EN 12697-26, see Appendix A).

Empirical approach

A specifications method currently employed in EN standards that consists of compositional recipes (particle size distribution curve, nature and content of binder, nature and rate of additives), aggregate characteristics, a general body of tests (percentage of voids, water resistance, wheel tracking) and "empirical" tests (or performance-based testing), such as Marshall stability and percentage of voids after 10 gyrations on the gyratory

Series EN 13108

All standards in the series contain an empirical approach


- 182 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

compactor.

Bitumen with anti-stripping agent

Bitumen containing an adhesion or anti-stripping agent. NF P 98-149

External binder content

TLext % ext. Ratio of the binder mass to the dry aggregate mass.

Use of the ppc notation to designate the units of this magnitude is erroneous.

Fatigue resistance

ε6 µdef Deformation admissible at 106 cycles, according to the fatigue test result in EN 12697-24, Annex A, usually at 10°C and 25 Hz.

Filler aggregate An aggregate whose grains pass the 0,063-mm sieve and that can be added to construction materials to provide them with certain characteristics.

EN 13043

Fine aggregate Designation of small-sized granular categories, for which D is less than or equal to 2 mm and whose non-passing rate through the 0,063 mm remains high.

EN 13043

Fines Particle size fraction of an aggregate which passes the 0,063 mm sieve.

EN 13043

Fines content (or total fines content) of the mixture

Tf % % passing the 0,063-mm sieve.

Flakiness FI The shape of coarse aggregate is determined in terms of the flakiness index. FI25 is the generally retained category. For very thin layers intended mixtures, category FI20 may be necessary.

Formula of a mixture (or the

Description of a unique mixture on which a mix design test has been performed. The


- 183 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

nominal formula, target formula or theoretical formula)

formula comprises the mass composition of all mix components, their origin, a particle size distribution curve and the results of tests conducted on a representative sample.

Formula verification

Assessment comprising a test or series of tests conducted on a mix design with components of the same origin (e.g. same extraction site, same crushing/screening facility) as the design to be verified, as characterized in particular by a particle size distribution curve and binder content.

Fundamental approach

A specifications method currently employed in European standards that consists of compositional indications (potentially a particle size distribution range [rather broad], potentially the type of binder and additives), aggregate characteristics, a general body of tests (percentage of voids, water resistance, wheel tracking), and other "fundamental" tests, such as stiffness modulus, fatigue resistance and repeated compression.

Series EN 13108.

Only applicable to asphalt mixes (EN 13108-1) and Hot Rolled Asphalt (EN 13108-4)

Gap-graded grading curve

Absence of one or several intermediate fractions within a granular recomposition.

Grading analysis See Particle size distribution

Grading characteristics of coarse aggregate

GC85/20

GC85/20, category of d/D fraction defined by:

• passing to D sieve between 85 % and 99 %

• passing to d sieve between 0 % and 20 %

• 100 % to 2 D sieve

• 0 % to 5 % to d/2 sieve.

EN 13043


- 184 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

GC85/15

GC85/15 category defined by: passing to d sieve between 0 % and 15 %, instead of 20 % and for single size coarse aggregate D/d, where D/d < 2, which is the case for gap-graded mixtures used in surface course, passing to D sieve between 90 % and 99 %, 100 % to 2 D sieve, 0 % to 5 % to d/2 sieve]

EN 13043

Generally required for gap-graded mixtures

G25/15

G20/15

G25/15 category of a fraction d/D is defined by a percentage passing at mid-size sieve [D/1,4], between 25 % and 80 % and G20/15 is defined by a percentage passing at mid-size sieve between 20% and 70%, with in both cases, a tolerance on the typical grading of ± 15 %, declared by the producer.

EN 13043

f1

f0,5

The fines content of coarse aggregate is measured by the percentage of passing at 0,063 mm sieve. Category f1 means ≤ 1 % at 0,063 mm sieve and category f0,5 means ≤ 0,5 % at 0,063 mm sieve.

EN 13043

GF85

GF85 category of fine aggregates 0/2 which is defined by:

• 100% passing at the 4 mm sieve

• between 85% and 99% at the 2 mm sieve.

GTC10

GTC10 Tolerances applied to the particle size distribution of fine aggregate defined by:

• ± 5% at D,

• ± 10% at D/2,

• ± 3% at 0,063 mm.

Grading characteristics of fine aggregate

f16

f22

Fines content category from fine aggregate which corresponds respectively to a fine content of 16% or 22%.


- 185 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

GA85

Category of all in aggregate with following characteristics:

• passing 100% at 2D,

• 98 to 100% at 1,4D,

• 85 to 99% at D.

Grading characteristics of all in aggregate

GTC10

GTC10 Tolerances applied to the particle size distribution of all in aggregate defined by:

• ±5% at D,

• ±10% at D/2,

• ±3% at 0,063 mm.

Granular compacity

Cg % Ratio, expressed as a percentage, of the aggregate volume within a bituminous mixture to the total specimen volume.

Grave-Bitume AC-GB

Bituminous mixture, as per EN 13108-1, designed to yield lower and upper base courses with a thickness between 8 cm and 16 cm. AC-GB are classified into 4 categories. They are relevant either of the empirical approach (Essentially AC-GB1, AC-GB2 and AC-GB3) or the fundamental approach (Essentially AC-GB2, AC-GB3 and AC-GB4).

Hard paving grade bitumen Bitumen output from refining to a grade

lower than paving bitumen (<20/30) and used to produce asphalt mixes with high stiffness modulus values.

EN 13924

Harmfulness of fine aggregates

MBF g/kg The harmfulness of fine aggregates and fines (< 0,125 mm) making up bituminous mixtures is evaluated by means of the methylene blue test, performed on the 0/0,125 fraction.

EN 933-9

Typical value: MBF10

High-modulus (stiff) asphalt concrete

AC-BBME

Bituminous mix, as per EN 13108-1, whose stiffness modulus is higher than that of a AC-BBSG mixture and that has been designed to yield surface or binder coarse of a thickness greater than or equal to 5 cm.


- 186 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

High-modulus bituminous mixture

AC-EME

High-modulus (stiff) bituminous mixture, in accordance with EN 13108-1. This material is used for base courses and is relevant from “fundamental approach”

Hot Rolled Asphalt

HRA Dense, gap-graded bituminous mixture in which the mortar of fine aggregate, filler and high viscosity binder are major contributors to the performance of the laid material. The proportion of fine aggregate is high (on the order of 50%), while the fines content stands at approximately 9%; coarse aggregates only represent 30% of the total mixture. The bitumen content lies on the order of 7% to 8%. The percentage of voids is very low; when used on wearing courses, this material is chipped with 10/16 or 10/20 coarse aggregates.

EN 13108-4

Hydrocarbon binder

A generic term used to designate an adhesive material containing bitumen, tar or both.

EN 12597

Input target composition

Expression of a mix formulation in terms of the constituent materials, the grading curve and the percentage of bitumen added to the mixture. This will usually be the result of a laboratory mix design and validation. The French approach is usually based on the “Input target composition”

EN 13108 series

Internal binder content

B

tlint

Tl

% (int.)

Ratio of the binder mass to total mixture mass. It is expressed as B in EN version as tlint in some French standards and as Tl in the French version of the EN standards.

The EN asphalt mix "product" standards from the EN 13108 series dictate the B (tlInt) value.

Layer

Element of pavement laid in a single operation.

EN 13108 series

Lime

Material comprising any physical and chemical forms under which calcium and/or magnesium oxide and/or hydroxide can appear.

EN 459-1


- 187 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Air lime Limes mainly consisting of calcium oxide or hydroxide which slowly harden in air by reacting with atmospheric carbon dioxide. Generally they do not harden under water as they have no hydraulic properties. They may be either quicklimes or hydrated limes.

Loss of linearity Γ - Relative decrease in modulus of a bituminous mixture as the yield strength increases. This determination is a special aspect of the direct tensile test described in Standard NF P 98-260-1, which has not been included in the European Standard EN 12697-26. The test is conducted at 0°C and the specimen is submitted to successive tensile forces for 30-second load times (and then reset to zero). The deformation rises from 50 10-6 to 500 10-6. Loss of linearity is the relative drop in modulus value at a deformation of 500 10-6 as a ratio of the modulus decrease obtained at zero deformation. The modulus at zero deformation can be obtained by means of extrapolation.

The loss of linearity provides an indication on the state of material damage.

Lower thermal susceptibility bitumen

A special bitumen, whose ring and ball temperature is higher than that of the corresponding paving grade bitumen.

Manufactured aggregate

An aggregate of mineral origin resulting from an industrial process involving thermal or other modifications.

EN 13043

Maximum density

ρmv MVR

g/cm3

or kg/m3

or Mg/m3

Ratio of the mass of a test specimen to its absolute volume, i.e. without incorporating the voids. Maximum density is determined according EN 12697-5, Method A using water.

ρmv

(maximal density by volumetric procedure)

Mix design Procedure consisting of adjusting, using a minimum number of tests, the composition of a formula so that it is able to satisfy all design testing requirements and ultimately other requirements as well.


- 188 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Mix formulation Composition of a single mixture expressed as target composition. It may be expressed as “input target composition” or as “output target composition”

EN 13108 series

Mixed filler Filler of a mineral origin mixed calcium hydroxide.

EN 13043

Natural aggregate

An aggregate from mineral source which has been subjected to nothing more than transformation other than mechanical.

EN 13043

Non-connecting voids

Voids in a test specimen open at one face, yet unable to reach the other face.

Noxious potential of fines

See harmfulness of fine aggregates.

Occluded voids Voids in the test specimen that do not open onto any of the specimen faces.

Output target composition

Expression of a mix formulation in terms of the constituent materials and the mid point grading and soluble binder content to be found on analysis. This will usually be the result of a production validation.

EN 13108 series

Particle size distribution or grading analysis

% The dimensional distribution of grain sizes, expressed in terms of mass percentage passing through a specified series of sieves. The analysis is carried out in accordance with EN 933-1 for aggregates in general and with EN 12697-2 for aggregates stemming from stripping operations.

EN 13043

Pavement

Structure, composed of one or more courses, to assist passage of traffic over terrain.

EN 13108 series


- 189 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Paving bitumen Bitumen used to coat mineral aggregate for use in the construction and maintenance of paved surface. In Europe, the most used grades are defined by needle penetration at 25°C, up to a value of 900 1/10 mm.

EN 12597

Percentage of laboratory voids characteristic of the bituminous mixture

PVL % Value deduced by the mix designer, based on void percentages measured on the test specimens produced in the laboratory using various means of compaction.

Percentage of voids

v % The air void is the pocket between the bitumen coated aggregate particles in a compacted bituminous specimen. The air void content or percentage of voids is the volume of the air voids in a bituminous specimen, expressed as a percentage of the total volume of that specimen.

EN 12697-8

Percentage of voids filled by bitumen

VFB % Binder volume as a ratio of total void volume in the granular skeleton, expressed as a percentage.

EN 12697-8

Percentage of voids in the mineral aggregate

VMA % Percentage of the pore and interstice volume in the granular skeleton as a ratio of total specimen volume. This value includes the percentage of voids in the mixture and the percentage volume occupied by the binder.

EN 12697-8

Pigmentable bitumen

A special bitumen category characterized by a low asphaltene content, which facilitates the coloration of asphalt mixes through adding pigments.

EN 12597

Polymer-modified bitumen

BmP

Modified bitumen materials are bituminous binders whose properties have been altered through the use of a chemical agent, which when introduced into the

EN 14023


- 190 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

basic bitumen modifies the chemical structure and the physical and mechanical properties.

These bitumens are prepared prior to application within a specialized unit. The chemical agents employed include natural rubber, synthetic polymers, sulfur and certain organic-metallic compounds; they do not include oxygen, oxidation catalysts, fibers, mineral powders or adhesion agents.

Porous asphalt PA-BBDr

Porous asphalt, in accordance with EN 13108-7.

Bituminous mixture in accordance with EN 13108-7, characterized by a percentage of voids exceeding or equal to 20% and a void shape such that rainwater is able to circulate into the connecting voids; this material is designed to yield surface courses with an average thickness of 3-4 cm (PA6) and 4-5 cm (PA10).

Pure bitumen Conventional bitumen obtained by means of various refining processes using crude oil as a base. No additive is included for the purpose of modifying the material's consistency.

NF P 98-149

Reclaimed asphalt

RA or AE

Granular materials stemming from either the milling or demolition of asphalt mixes and entering into the composition of recycled mixes.

NF P 98-149

EN 13108-8

Recycled aggregate

An aggregate resulting from processing of inorganic materials previously used in construction.

EN 13043

Regulating course Course of variable thickness applied to an

existing course to provide the necessary profile for a further course of consistent thickness.

EN 13108 series

Repeatability Reliability of measures under conditions of repeatability, i.e.: conditions according to

ISO 5725


- 191 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

which the results of independent tests are obtained using the same method on identical test specimens, in the same laboratory, by the same operator, in employing the same equipment and over a short span of time.

Repeatability limit

r Value below which the absolute value of the difference between two test results lies, with 95% probability, as obtained according to repeatability conditions.

Reproducibility Reliability of measures under conditions of reproducibility, i.e.: conditions according to which test results are obtained using the same method on identical test specimens, in different laboratories, by different operators, in employing different equipment.

ISO 5725

Reproducibility limit

R Value below which the absolute value of the difference between two test results lies, with 95% probability, as obtained according to reproducibility conditions.

Richness modulus

Conventional specific surface area

Σ m2/kg Determined by the following relation:

100 Σ = 0,25 G + 2,3 S + 12 s + 150 f, with:

G proportion of elements larger than 6,3 mm,

S proportion of elements lying between 6,3 mm and 0,250 mm in size,

s proportion of elements between 0,250 mm and 0,063 mm

f proportion of elements smaller than 0,063 mm

This calculation is not applicable when the mixture contains either special fines or additives, such as fibers.

Richness modulus

Correction coefficient

α α = 2,65 / ρG with ρ

G being the aggregate

mass density in terms of grams per cubic centimeter.

This coefficient is employed in particular to calculate bitumen contents on the basis of the richness modulus.


- 192 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Richness modulus

K A magnitude proportional to the conventional thickness of the bituminous binder film coating the aggregate. K is independent of the granular mix density and well correlated with binder content by the following equation:

5 Σα×= KTL

where Σ is the conventional specific surface area,

α a correction coefficient

Rigden: Void of dry compacted filler

V Determination of the percentage of voids in a filler compacted by (100) shocks in a cylinder.

Test standard: EN 1097-4.

EN 13043

Typical values:

V28/45

Ring and ball temperature

°C Two bitumen disks, molded into brass rings with shoulders, are heated in a liquid solution at a controlled rate of temperature rise, with each supporting a steel ball. The observed softening temperature must correspond to the average temperature at which the two disks are softening enough to allow each bitumen-coated ball to fall from a height of 25,0 mm ± 0,4 mm.

EN 1427

Secant modulus E(θ, t) MPa Modulus obtained at a temperature θ in °C and for a load time of t in seconds (European Standard EN 12697-26, see Appendix E).

Asphalt Concrete – Béton Bitumineux Semi-Grenu

AC-BBSG

Bituminous mix, in accordance with EN 13108-1, characterized by a high coarse aggregate content and designed to yield surface or binder courses with a thickness between 5 cm and 9 cm.

« Semi-coarse asphalt concrete »

Sensitivity analysis

An optional experimental design, prescribed on certain composition variants or percentage of void deviations in order to characterize mixtures that deviate from the nominal composition or that display different percentages of voids.


- 193 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Shape of coarse aggregate

FI See Flakiness Index

Lower dimension of a granular fraction or bituminous mixture

d mm Dimension, chosen in the base series + series 1 or + series 2, corresponding to the grain size determined with a particle size distribution analysis by means of sieving, such that the majority of grains do not pass. This definition acknowledges that grains are capable of passing the sieve of dimension d, according to the categories and within the limitations prescribed in Standard EN 13043. Conditions are imposed upon the sieve with opening d/2.

Soft bitumen Paving bitumen used in the manufacture of soft asphalt. In Europe, grades of soft bitumen are defined by their viscosity at 60°C.

Standard penetration of a bituminous binder

0,1 mm

Consistency corresponding to the vertical penetration of a reference needle in a material test sample, under a set of prescribed conditions on temperature, load and load application time. The standard penetration corresponds to a temperature of 25°C, a load of 100 g and an application time of 5 s.

EN 1426

This test serves to categorize bitumen types, especially in EN 12591, e.g. 35/50 vs. 50/70.

Stiffness modulus

E MPa Ratio of the stress at a relative deformation submitted to a specimen during a mechanical test. This value serves to characterize the level of material stiffness. For bituminous materials, the stiffness modulus value must be accompanied by the temperature and loading time or frequency during the test period.

Stone mastic asphalt

SMA Gap-graded mixture with bitumen as binder, composed of a coarse crushed aggregate skeleton bound with a mastic mortar. Mixture with a particle size range lying between 0/4 and 0/20, characterized by a high proportion of coarse aggregates and mastic. Bitumen content is also high; fibers are incorporated, if need be to decrease the risks of drainage.

EN 13108-5


- 194 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Surface course

Upper course of a pavement which is in contact with the traffic.

EN 13108 series

Synthetic binder A binder obtained by mixing petroleum and petrochemical fractions without any asphaltene. This binder appears as a thin transparent film, which makes it possible to retain the natural hue of the aggregate; moreover, it can be colored by adding pigments.

Thin layer asphalt concrete

AC-BBM

Bituminous mix, in accordance with EN 13108-1, characterized by an average application thickness of between 3 and 5 cm; material intended to yield limited thickness surface (or binder) layers. Category A is 2/6 gap-graded, Category B is 2/4 gap-graded, Category C is continuously graded.

The particle size distribution curve is most often gap-graded.

Type testing Predefined sequence of laboratory tests conducted on a given composition mixture for the purpose of determining characteristics that satisfy a set of established requirements.

Type testing Level 0

Assessment containing a description of the mix without further testing


Assessment featuring both a Gyratory Compaction test for determination of the void content and a water-sensitivity test according EN 12697-12, method B, specimen preparation in compression.


Assessment containing all of the Level 1 tests plus a wheel tracking test (large device).


Assessment containing all Level 2 tests plus stiffness modulus tests.


Assessment containing all Level 3 tests plus a fatigue test (EN 12697-24-Annex A).

Upper dimension of an aggregate or bituminous

D mm Sieve dimension, as chosen in the base series + series 1 or + series 2, corresponding to the grain size determined


- 195 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

mixture with a particle size distribution analysis analyze by means of sieving, such that the majority of grains pass (between 85% and 99% depending on the specific case). This definition acknowledges that grains are capable of not passing the sieve of dimension D, according to the categories and within the limitations prescribed in Standard EN 13043. Conditions are imposed upon the sieve of opening 1,4 D.

Béton Bitumineux Très Mince

Very thin layer asphalt concrete

BBTM Bituminous mix, in accordance with EN 13108-2, characterized by an average application thickness of between 2 and 3 cm; material intended to yield surface courses.

Void of dry compacted filler

Rigden

V Determination of the percentage of voids in a filler compacted by (100) shocks in a cylinder.

Test standard: EN 1097-4.

EN 13043

Typical values: V28/45

Volume of absorbed bitumen

vba Volume of bitumen penetrating into the aggregate pores.

Warm asphalt

Half warm asphalt

Specific process intended to reduce the mixing and the compaction temperature of the bituminous mixture without compromising the characteristics of the mixture. The lower mixing temperature is obtained by decreasing the viscosity of the binder using for example special binder with a wax addition, double coating (soft and hard grade bitumen), addition of foaming agent, presence of water due to specific additives or to wet cold constituents in order to have a foaming effect on the binder.

If the mixture is produced at a temperature below 100°C, it is considered as “Half warm asphalt”.


- 196 -

Term

Sym

bol o

r A

bbre

viat

ion Uni

t

Definition Comments

Zeolite Crystalline hydrated aluminium silicate, which contains part of water. When it is added to the mix at the same time as the bitumen, water is released and creates an bitumen foam which allows increased workability. Used as additive for Warm Asphalt technology.

LPC Bituminous Mixtures Design Guide - Index -

- 197 -

Index

A AC-BBME, 44, 47, 56, 59, 60, 61, 64, 80,

90, 91, 101, 111, 115, 185 AC-BBS, 43, 44, 47, 64, 91, 177 AC-BBSG, 41, 44, 47, 56, 59, 60, 61, 64,

75, 77, 80, 90, 91, 103, 104, 110, 111, 113, 115, 128, 140, 164, 185, 192

AC-EME, 41, 43, 47, 56, 59, 60, 61, 62, 64, 86, 87, 88, 101, 106, 111, 115, 116, 117, 125, 139, 140, 186

AC-GB, 41, 47, 59, 60, 61, 64, 75, 85, 86, 88, 103, 104, 115, 128, 139, 140, 185

added filler, 26, 43, 55, 73, 74 additive, 25 additives, 35, 41, 48, 73, 74, 81, 82, 85,

86, 91, 93, 96, 100, 114 additives, 30 airfields, 44, 52, 66, 149

B basalt, 26, 49, 85, 90, 128 binder content, 5, 17, 19, 21, 34, 37, 39,

40, 50, 51, 52, 53, 54, 56, 57, 64, 66, 75, 85, 86, 87, 88, 90, 92, 94, 95, 97, 98, 99, 100, 102, 105, 111, 113, 116, 124, 127, 131, 151, 154, 156, 157, 164, 166, 167, 168, 169, 170, 171, 172, 180, 182, 183, 186, 188, 192

bitumen, 18, 20, 27, 28, 29, 30, 31, 32, 35, 36, 38, 39, 40, 48, 49, 52, 54, 55, 62, 64, 66, 67, 68, 69, 70, 75, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 89, 91, 93, 95, 96, 99, 100, 101, 104, 105, 106, 110, 111, 113, 114, 115, 116, 117, 118, 120, 121, 122, 124, 128, 134, 140, 150, 154, 155, 164, 166, 167, 168, 169, 170, 171, 172, 177, 178, 181, 182, 185, 186, 187, 189, 190, 191, 192, 193, 195, 196

bulk density, 37, 38, 40, 54, 62, 64, 66, 67, 68, 69, 70, 130, 151, 154, 178

C cement, 26, 49, 74 color, 82, 175 , 107

compacity, 22, 35, 38, 55, 75, 77, 78, 86, 101, 103, 104, 105, 106, 110, 113, 115, 116, 120, 122, 160, 185

D drainage, 62, 69, 71, 74, 82, 93, 114, 123,

153, 155, 193 Duriez, 145

E EME, 145

F fatigue, 4, 14, 15, 17, 18, 19, 20, 25, 35,

55, 56, 61, 65, 79, 82, 83, 84, 101, 117, 121, 122, 124, 125, 127, 131, 140, 141, 142, 144, 145, 146, 152, 156, 174, 177, 182, 183, 194

fibres, 35 filler, 5, 26, 32, 36, 42, 43, 55, 74, 75, 82,

86, 101, 150, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 178, 181, 186, 188, 192, 195

fine aggregate, 43, 44, 64, 75, 76, 77, 79, 85, 90, 101, 102, 109, 110, 113, 114, 115, 123, 124, 178, 184, 186

Fine content, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174

fines, 5, 26, 30, 35, 41, 42, 43, 44, 73, 74, 75, 76, 78, 82, 85, 90, 102, 104, 106, 107, 110, 113, 115, 124, 149, 182, 184, 185, 186, 188, 191

fly ash, 26, 74

G Grave-Bitume, 41, 85, 86, 87, 103, 185 graves-bitumes, 146 gyratory, 5, 15, 19, 20, 22, 35, 53, 55, 102,

103, 105, 114, 127, 142, 152, 154, 157, 170, 171, 181

I I/C, 74, 75, 86, 90, 93, 114, 115, 116, 164,

165, 166, 167, 168, 169, 170, 171, 172, 173, 174

LPC Bituminous Mixtures Design Guide – Index –

- 198 -

indirect tensile, 22, 55, 156

L limestone, 26, 30, 32, 74, 77, 85, 86, 90,

115, 176, 177

M Marshall, 18, 19, 64, 65, 66, 152, 156,

157, 181 mastic, 19, 36, 74, 75, 101, 123, 153, 178,

181, 193 maximum density, 37, 53, 54, 63, 64, 66,

67, 69, 70, 77, 87, 92, 94, 97, 99, 105, 151, 154, 157, 160, 179

module, 144, 145, 146 module de rigidité, 144, 145 MVR, 37, 38, 39, 53, 54, 64, 66, 67, 68,

70, 77, 87, 92, 94, 97, 99, 105, 160, 179, 187

N natural asphalt, 49

O oxides, 29, 33

P PCG, 146 penetrability, 28, 29, 30, 48, 83 permeability, 62, 71, 153, 155 PmT, 123 polymer, 28, 48, 80, 91, 93, 96, 151, 154 polymer modified, 151, 154 polymères, 144 porous, 37, 50, 62, 70, 74, 96, 101, 152,

155 Porous Asphalt, 46, 92, 93, 95, 123

Presse à Cisaillement Giratoire, 145, 146 pseudo shear stress, 105

R Resistance to deicing products, 66, 67, 68,

69, 71 Resistance to fuels, 66 Richness modulus, 191, 192 ring and ball, 28, 29, 30, 32, 48, 80, 83,

86, 113, 150, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 181, 187

rubber, 27, 28, 29, 31, 82, 189

S slope, 83, 102, 104 SMA, 82, 98, 99, 123, 193 stiffness, 4, 15, 19, 20, 23, 28, 55, 56, 60,

61, 62, 65, 79, 81, 83, 84, 86, 89, 101, 116, 118, 119, 120, 122, 124, 125, 127, 131, 136, 137, 139, 140, 142, 165, 173, 174, 177, 183, 185, 193, 194

Synthetic binders, 81

T type testing, 18, 19, 20, 33, 41, 42, 44, 54,

56, 57, 60, 62, 63, 64, 66, 73, 79, 102, 153, 154

W water resistance, 19, 22, 35, 55, 57, 59,

60, 61, 63, 74, 79, 83, 85, 86, 90, 93, 101, 109, 114, 115, 124, 181, 183

water sensitivity, 152, 155 wheel tracking, 23, 44, 55, 56, 58, 60, 61,

62, 65, 76, 78, 79, 85, 89, 110, 132, 133, 134, 135, 172, 181, 183, 194

Date post:	24-Jun-2020
Category:	Documents
Upload:	others
View:	8 times
Download:	9 times

LPC Bituminous Mixtures Design Guide …aapaq.org › MC2012 › PAB ›...

Documents