Lab and field eveluation of recycled cold mix

Laboratory and Field Evaluation of Recycled Cold Mixes I

Dissertation report on

“LABORATORY AND FIELD EVALUATION OF RECYCLED COLD MIXES”

Submitted in partial fulfillment for award of the degree of

MASTER OF TECHNOLOGY In

TRANSPORTATION ENGINEERING (2004-2006)

Submitted by: G.NARENDRA GOUD Under the guidance of

DR. SUNIL BOSE Head,

Flexible Pavements Division, CRRI-New Delhi

SHRI ARUN GAUR Lecturer

Department of Civil Engineering MNIT-Jaipur

DEPARTMENT OF CIVIL ENGINEERING

MALAVIYA NATIONAL INSTITUTE OF TECHNOLOGY

(DEEMED UNIVERSITY)

JAIPUR (RAJASTHAN)-302017

Laboratory and Field Evaluation of Recycled Cold Mixes II

CERTIFICATE

This is to certify that the Dissertation report entitled “LABORATORY AND

FIELD EVALUATION OF RECYCLED COLD MIXES” being submitted by

Mr. G. NARENDRA GOUD (College ID -046126) to the Department of civil

engineering, Malaviya National Institute of Technology-Jaipur, in partial fulfillment

for the award of Master of Technology in Transportation Engineering is a bona fide

work carried out by him under our guidance and supervision.

The contents of this dissertation, in full or in parts, have not been submitted to any

other institute or university for the award of any degree or diploma.

Place: New Delhi Date: / 6/ 2006

(Dr. SUNIL BOSE)

Head, Flexible Pavements Division,

CRRI-New Delhi

(Shri ARUN GAUR) Lecturer

Department of Civil Engineering MNIT-Jaipur

Laboratory and Field Evaluation of Recycled Cold Mixes III

ACKNOLEDGEMENTS I would like to express my sincere gratitude to Dr. P.K. Nanda, Director, Central Road Research

Institute, New Delhi for permitting me to carryout my dissertation work in Flexible Pavements

Division, CRRI.

It is most pleasant to express hearty gratitude to my external guide Dr Sunil Bose, Head flexible

pavements division-CRRI, who has given me the opportunity and under whose supervision I was

able to do my dissertation work. Words can not do much justice to the guidance and help given by

him.

I sincerely express my deep gratitude to my internal guide Shri. Arun Gaur, Lecturer, Department

of Civil Engineering and Shri. Girish shrma for their guidance and support.

I am very much thankful to Shri. Subhash Niyogi, Managing Director of Wirtgen India Private

Limited, for providing me all the facilities in carrying out the study. I am grateful to all the

employees of Wirtgen India Private Limited-Bangalore whoever helped me during my association

with the firm. And also I’m very thankful to Devendhar Singh Bisth, Quality control engineer,

Nagarjuna Construction Company (NCC) Pvt. Ltd. for aiding me the laboratory facilities at their

project site Bidadi-Bangalore.

Laboratory and Field Evaluation of Recycled Cold Mixes IV

My Hearty Gratefulness and thanks to Dr. Pawan Saluja, Shri. Gajender Kumar, Shri Manoj

Shukla, Dr. Sangitha and CRRI-Flexible Pavements Division staff for their encouragement,

technical guidance and support during my laboratory study.

I would like to thank Dr Rohit Goyal, Head Department of Civil Engineering, Malaviya National

Institute of Technology, Jaipur. for giving me the permission to do my dissertation work at CRRI.

I would like to thank Dr. Krishna Murthy, Head Department of Civil Engineering, Bangalore

University who has accepted immediately to conduct BBD study on the test track.

My special thanks to Shri. Pawan Kalla, Lecturer Department of Civil Engineering, Malaviya

National Institute of Technology, Jaipur and Shri. Sridhar Raju, Scientist, CRRI. who

encouraged and supported me to do my dissertation work at CRRI-New Delhi.

Last but never the least; I would like to state my deep gratitude for all the support given

required from time to time, by my parents and all my friends.

Once again I thank one and all who have helped me directly or indirectly in completion of

my dissertation work.

(G. Narendra Goud)

Laboratory and Field Evaluation of Recycled Cold Mixes V

ABSTRACT

In the dense populated cities like Delhi, where environmental pollution and Land fill problems are

of prime concerns in the recent years. In rapid developing countries like India, where conservation

and optimum utilization of the road building materials specially petroleum and mineral products

are an important issue. There is an immediate attention requirement towards the development and

implementation of Ecofriendly and cost effective pavement construction technologies. Through

application of these technologies the efficient use of existing and waste materials can be made

with out creating problems to the environment and at the same time meeting the quality

requirements of the pavements.

Advances in technology and techniques in the in recent years have made cold recycling an

increasingly popular and cost-effective pavement construction and maintenance technique. In the

present study an effort is made to study the laboratory and field behaviour of recycled cold mixes

with binders as an emulsion and foamed bitumen. The Marshall specimens were cast using

emulsion and foamed bitumen in combination with different types of fillers such as cement, lime

and fly-ash. The specimens were tested for density, Indirect Tensile Strength, Resilient modulus

and dynamic creep. Benkelman Beam deflection study was carried out on the pavement

constructed with recycled foamed bituminous mix after a period of three months from construction

and field cores were cut from the pavement and were investigated in the Laboratory. It was found

that the pavement constructed with foamed bitumen treated RAP was structurally sound and cores

cut from that pavement have shown higher ITS and MR values when compared with Laboratory

cast cores but they shown less creep stiffness and densities. In comparison with emulsion treated

RAP, foamed bitumen treated RAP shown higher density, ITS, MR and creep stiffness with same

aggregate and gradation.

Laboratory and Field Evaluation of Recycled Cold Mixes VI

CONTENTS

S.NO. TITLE Pg NO

1. INTRODUCTION......................................................................................................................1

1.1 General .................................................................................................................................1

1.2 Objectives.............................................................................................................................2

1.3 Scope of Work .....................................................................................................................2

1.4 Methodology Adopted .........................................................................................................2

2. LITERATURE REVIEW ..........................................................................................................3

2.1 Why Milling? .......................................................................................................................3

2.2 Why Recycling?...................................................................................................................3

2.3 Methods of Pavement Recycling .........................................................................................4

2.4 Candidates for Recycling .....................................................................................................5

2.5 Advantages of Cold Recycling ............................................................................................6

2.6 Bitumen Emulsion................................................................................................................7

2.7 Bitumen Emulsion Classification.........................................................................................8

2.8 Recycling With Bitumen Emulsion .....................................................................................9

2.9 Foamed Bitumen ................................................................................................................12

2.10 Characterization of Foamed Bitumen ..............................................................................13

2.11 Factors influencing foam properties ................................................................................14

2.12 Dispersion of foamed bitumen.........................................................................................16

2.13 Material suitability for foamed bitumen treatment ..........................................................17

2.14 Recycling with foamed bitumen ......................................................................................19

2.15 The benefits of foamed bitumen stabilisation ..................................................................26

2.16 Case studies......................................................................................................................29

Experience in India: .................................................................................................................29

2.16.1 Emulsion Cold Recycling Rehabilitation Project-Hyderabad ......................................29

2.16.2 Foam bitumen cold recycling rehabilitation project-Bangalore ...................................35

Experience in abroad:...............................................................................................................40

2.16.3 Emulsion Cold Recycling Rehabilitation Project. Citizen Court, Toronto, June 2003 40

Laboratory and Field Evaluation of Recycled Cold Mixes VII

2.16.4 Saudi Arabia – A desert road for heavy traffic .............................................................45

2.16.5 In-Plant recycling using milled asphalt bound with foamed bitumen ..........................47

3. LABORATORY AND FIELD STUDY ......................................................................................55

3.1 RAP and Mineral Aggregate Evaluation ...........................................................................55

3.2 Foamed Bitumen Characterization.....................................................................................55

3.3 Emulsion Testing ...............................................................................................................59

3.4 Mineral Aggregate Proportions..........................................................................................59

3.5 OMC Determination for Foamed Bitumen Treatment.......................................................64

3.6 OFC Determination for Emulsion Treatment ....................................................................65

3.7 Recycled Cold Mix Preparation with Foamed Bitumen ....................................................66

3.8 Recycled Cold Mix Preparation with Emulsion ................................................................69

3.9 Foamed bitumen and Bitumen Emulsion treated RAP Specimen testing..........................70

3.10 Benkelman Beam Deflection testing................................................................................76

4. RESULTS AND ANALYSIS .....................................................................................................77

4.1 Results of Foamed Bitumen Treated RAP Marshall Specimens .......................................77

4.2 Results of Emulsified Bitumen Treated RAP Marshall Specimens...................................85

4.3 Field and Laboratory Core Comparison.............................................................................89

4.4 Dynamic Creep Test Results Analysis...............................................................................90

5. CONCLUSIONS AND RECOMMENDATIONS ......................................................................92

6. APPENDICES ..........................................................................................................................93

Appendix 1: Material Sampling and blending .........................................................................93

Appendix 2: Mix Design Procedure for Bitumen Stabilised Materials ...................................95

Appendix 3: Strength Test Procedures...................................................................................105

7. REFERENCES.......................................................................................................................108

Laboratory and Field Evaluation of Recycled Cold Mixes VIII

LIST OF FIGURES

Figure 2.1: Example of fluid considerations for a bitumen emulsion stabilised material 10

Figure 2.2: Schematic diagram of foamed bitumen production 12

Figure 2.3: Bitumen Foam characterization 14

Figure 2.4: Foamed bitumen dispersion and binding in the treated mix 17

Figure 2.5: Material gradation envelops 18

Figure 2.6: A view of recycling process progress in Hyderabad 31

Figure 2.7: Aggregate Spread over the layer to be recycled to correct the Gradation 31

Figure 2.8: Recycling crew in action 32

Figure 2.9: Recycled layer after pre compaction 32

Figure 2.10: Compacting the recycled layer 33

Figure 2.11: Tack coat application over the recycled and compacted layer 33

Figure 2.12: Finished surface of the recycled layer 34

Figure 2.13: Loader used to load the materials in to the mobile plant 37

Figure 2.14: Cement and hot bitumen supplied to the plant 37

Figure 2.15: Recycled material being discharged in to the dumper 38

Figure 2.16: Recycled foamix being dumped in to the paver hopper 38

Figure 2.17: Initial compaction with vibrator roller 39

Figure 2.18: Final compaction with pneumatic tyred roller 39

Figure 2.19: Recycling option used 42

Figure 2.20: Emulsion tanker and recycler 42

Figure 2.21: Pre-compacted surface after 1st pass 43

Figure 2.22: Cold milling from kerb outwards 44

Figure 2.23: Pre-compacted surface after 2nd pass 45

Figure 2.24: Recycling of Shaybah Access road 46

Figure2.25: The Hartl Powercrusher PC 1270 I Impact crusher being used to crush the RAP

material 50

Figure2.26: The Wirtgen KMA 200 cold mixing plant utilized to dose and mix the binding

agents and water with the RAP 50

Laboratory and Field Evaluation of Recycled Cold Mixes IX

Figure 2.27: Vogele 1800 paving the foamed bitumen treated base material directly onto the

road as an overlay 51

Figure 2.28: Compaction done with HAMM HD O70V double drum Oscillation /

Vibration roller and HAMM GRW 18 pneumatic tyred roller 51

Figure2.29: The road surface being moistened with water during final compaction and

just before traffic is allowed onto the base course 52

Figure2.30: The longitudinal joint being moistened before paving of the second road-width52

Figure 2.31: Paving of the second road width and traffic on the freshly compacted material.

This layer was kept moist for the first couple of hours for curing purposes 53

Figure2.32: The finished cold recycled base course after being trafficked for several days 53

Figure2.33: The Tack coat applied by a hand sprayer on one half of the base course 54

Figure2.34: Paving and compaction of the 4 cm asphalt wearing course 55

Figure3.1: WLB 10- Wirtgen foamed bitumen lab kit 57

Figure3.2: Air pressure Influence on expansion ratio and half time of Foamed bitumen 58

Figure3.3: Bitumen temperature Influence on expansion ratio and half time of Foamed

bitumen 58

Figure3.4: Bitumen water content Influence on expansion ratio and half life time of Foamed

bitumen 59

Figure3.5: option1 gradation curves 62



Figure3. 8: option4 gradation curves 63

Figure3.9: samples of separated RAP and stone dust 64

Figure3.10: OMC determination 64

Figure3.11: OFC determination 65

Figure3.12: Mineral aggregates used in the study 66

Figure3.13: WLB10 laboratory plant used to produce foamed bitumen 66

Figure3.14: Pug-mill type mixer used to prepare foamix 67

Figure3.15: Hobart mixer used to prepare emulsion mixture 69

Figure3.16: Indirect Tensile Strength Testing Schematic diagram 70

Figure3.17: Specimen setup of Indirect Tension Test for Resilient Modulus 71

Laboratory and Field Evaluation of Recycled Cold Mixes X

Figure3.18: Specimen setup of dynamic creep testing 71

Figure3.19: Benkelman Beam rebound deflection variation with distance 76

Figure 7.1 Determination of optimum foaming water content 100

LIST OF TABLES Table2. 1: The major uses of bitumen emulsion 07

Table2. 2: Bitumen emulsion classification and their recommended application.

(IS 8887-2004) 08

Table2. 3: Foamed bitumen dispersion (ability to mix) 20

Table2. 4: Typical foamed bitumen contents relative to key aggregate fractions 21

Table2. 5: Tentative binder and additional treatment requirements 22

Table2.6: Comparison between different types of bitumen applications 28

Table3. 1: Sieve analysis of pulverized and air-dried RAP 55

Table3. 2: Sieve analysis of Stone Dust 55

Table3. 3: Air pressure Influence on expansion ratio and half time of Foamed bitumen 57

Table3. 4: Bitumen temperature Influence on expansion ratio and half time of Foamed

bitumen 58

Table3. 5: Study of Bitumen water content Influence on expansion ratio and half life time

of Foamed bitumen 58

Table3. 6: Tests on Emulsion 59

Table3. 7: Different options of aggregate proportions 60

Table3. 8: Option1 Material proportions 60

Table3.9: Option2 Material proportions 60



Table 3.12: Material calculations for foamix preparation 68

Table 3.13 Foamed bitumen Specimen test results 72

Table 3.14 Bitumen Emulsion Specimen test results 74

Table3.15: Dynamic Creep Test results 75

Table3.16: Deflection data (LHS, towards Karnataka cold Storage Pvt. ltd) 76

Laboratory and Field Evaluation of Recycled Cold Mixes XI

Table3.17: Deflection data (RHS, towards Karnataka cold Storage Pvt. ltd) 76

Table4.1: Maximum bulk density values from the Graphs 4.1(a, b, c) 77

Table 4.2: Maximum Resilient modulus (MR) values from the Graphs 4.2(a, b) 80

Table4.3: Maximum Resilient modulus (MR) values from the Graphs 4.3 (a, b) 81

Table4.4: Maximum Resilient modulus (MR) values from the Graphs 5.6(a, b) 82

Table 4.5: Maximum Dry Indirect Tensile Strength (ITS) values from the Graphs 4.5 (a, b, c) 83

Table 4.6: Maximum soaked Indirect Tensile Strength (ITS) values 83

Table4. 7: Maximum bulk density values From the Graphs 4.6 (a, b) 85

Table4. 8: Maximum Resilient Modulus values from the Graphs 4.7 (a, b) 86

Table 4. 9: Maximum Dry and Soaked Indirect Tensile Strength (ITS) values from the Graphs 4.8

(a, b) and 4.9 (a, b) 87

LIST OF GRAPHS Graph4. 1:( a, b, c) Variation of bulk density with foamed bitumen and filler 78

Graph4.2 :( a, b) Variation of Resilient Modulus with foamed bitumen and Cement 80

Graph4.3 :( a, b) Variation of Resilient Modulus with foamed bitumen and Lime 81

Graph4.4 :( a, b) Variation of Resilient Modulus with foamed bitumen and Fly-ash 82

Graph4.5: (a, b, c) Variation of dry ITS with foamed bitumen 84

Graph4.6 :( a ,b) Variation of bulk density with Bitumen Emulsion 85

Graph4.7 :( a, b) Variation of Resilient Modulus with Bitumen Emulsion 86

Graph4.8: (a, b) Variation of ITS with Bitumen Emulsion and Cement 88

Graph4.9 :( a, b) Variation of ITS with Bitumen Emulsion and lime 88

Graph4.10 :( a, b, c) Variation of Resilient Modulus, Bulk density and ITS in

different cores 89

Graph4.12 :( a, b, c) Variation of Accumulated axial strain with Number of cycles 90

Graph4.11 :( a, b) Variation of Accumulated axial strain with Number of cycles 91

Laboratory and Field Evaluation of Recycled Cold Mixes 1

_________________________________________CHAPTER 1

1. INTRODUCTION

1.1 General

In the dense populated cities like Delhi, where environmental pollution and Land fill problems are

of prime concerns in the recent years. In rapid developing countries like India, where conservation

and optimum utilization of the road building materials specially petroleum and mineral products

and energy are an important issues. The rehabilitation and up gradation of existing badly

distressed Pavements due to rapidly growing heavy vehicular traffic are attracting the

concentration. There is an immediate attention requirement towards the development and

implementation of Ecofriendly pavement construction technologies. Through application of these

technologies the efficient use of existing and waste materials can be made with out creating

problems to the environment and at the same time meeting the quality requirements of the

pavements.

Advances in technology and techniques in the in recent years have made cold recycling an

increasingly popular and cost-effective pavement construction and maintenance technique. It has

been proved in abroad that cold recycling with emulsion or foamed bitumen is one of the best

alternatives to be considered as a rehabilitation option. Cold recycling technology can be an option

which has the potential to address the above mentioned issues.

In the present study an effort is made to study the laboratory and field behaviour of recycled cold

mixes with binders as an emulsion and foamed bitumen. The Marshall specimens were cast using

emulsion and foamed bitumen in combination with different types of fillers such as cement, lime

and fly-ash. The specimens were tested for density, Indirect Tensile Strength, Resilient modulus

and dynamic creep. Benkelman Beam deflection study was carried out on the pavement

constructed with recycled foamed bituminous mix after a period of three months from construction

and field cores were cut from the pavement and were investigated in the Laboratory.


1.2 Objectives • To study the suitability of cementitious and bituminous agents (Emulsion and Foamed

bitumen) for cold recycling

• To determine optimum content of stabilizing agent

• To study the performance of stabilized mix

1.3 Scope of Work In the present study stabilizing agents viz. cementitious and bituminous was investigated for its

use with Recycled Asphalt Pavement (RAP) material. The effect of different stabilizing agents and

their dosage on density, indirect tensile strength (ITS) and other performance parameters of

stabilized mix were studied.

1.4 Methodology Adopted Determination of foaming properties of bitumen viz. expansion ratio and half life using

Wirtgen WLB 10 foamed bitumen laboratory unit

Preparation of samples using different combinations of granular/RAP material and

stabilizing agents

Preparation of Samples of different combinations of cement, lime, fly-ash, emulsion and

foamed bitumen and testing for density and indirect tensile strength (ITS) to determine

optimum content of stabilizing agent

Determination of Stiffness of bitumen-stabilized material by subjecting 100 mm diameter

Marshall Specimen to repeated load testing

Study of Performance of test track laid with recycled asphalt pavement by evaluating cores

from the existing cold recycled pavement and testing for performance characteristics

Determination of structural adequacy of the Recycled foamed bitumen test track by

Benkelman beam deflection study


_________________________________________CHAPTER 2

2. LITERATURE REVIEW

2.1 Why Milling? Milling is the process of cutting away material by feeding a work piece past a rotating multiple

tooth cutter. It can be carried out when the pavement condition is in COLD or HOT. Cold milling

is considered to be more economical, ecofriendly in nature and can be done to pavement full

depth.

Earlier roads were designed for less traffic and lighter vehicle weights than found today. Many

roads are being distorted and failing prematurely as a result. Reestablishing a uniform surface is

essential if these roads are to be properly repaired. Milling provides a uniform surface for the

placement of new pavement. If rutted roads are overlaid as it is, insufficient material is placed in

the rutted area, producing low density in the areas of the ruts. By milling to a flat surface, recycled

material is created, the ruts are eliminated, and the new pavement will have a uniform density

across the entire lane. Milling can reestablish the proper road grade and slope and eliminate high

spots and ruts. Many times, milling can reduce or even eliminate reflective cracking. Better

leveling can be achieved by milling than by applying a leveling course of asphalt. Furthermore,

considerable savings result. Other very significant advantages are gained by milling and inlaying

on highway work are Shoulders do not have to be raised, Guard rails do not have to be raised

because the road elevation remains the same. Milling also provides utility accesses (i.e. drain

gullies, man holes, etc) to remain same. Bridge clearances remain the same, so clearance signs do

not have to be changed.

2.2 Why Recycling? Recycling:-The reuse, usually after some processing, of a material that has already served its first

intended purpose.

The reasons for, and advantages from, Recycled Asphalt (RA) being put back in to pavements can

be summarized in the fallowing simple points

• The use of already existing materials, the elimination of disposal problems and

conservation of natural resources (aggregates and petroleum products).


• Major energy savings, including those related to avoiding processing of additional virgin

material and the potential for reduced haulage of materials with associated reduction in

energy emissions and congestion.

• A cost reduction with respect to other conventional methods of restoring former properties

of the road.

Furthermore, adding RA also provides:

• The opportunity to modify the grading of the aggregate and/or the properties of the binder

in the existing asphalt in order to improve the properties of in-situ mixture.

• The opportunity to correct the profile and/or the cross fall of the pavement and improve the

smoothness and ride quality.[1]

2.3 Methods of Pavement Recycling Pavement may be recycled in-place or in-plant depending on various factors such as availability of

equipment, existing material quality and requirement of the quality control over the treated

material.

An in-situ or in-place recycling process involves a train of machines planing out, and then

immediately processing, the material and relaying it without removing it from site. In-situ

recycling is usually preferred because it is less costly (with the elimination of costs associated the

stockpiling, handling, maintaining an inventory and long distance hauling of the reclaimed

material) and because it causes less disruption to the traffic.

An off-site or in-plant recycling process involves processing the material in a central plant (often

far from the works location) or in a mobile recycling plant just near the works location.

The Asphalt Recycling and Reclaiming Association (ARRA) recognizes five types of asphalt

pavement recycling:

i. Cold planing

ii. Hot recycling

iii. Hot in-place recycling

iv. Cold recycling and

v. Full-Depth Reclamation

Cold planing:- The asphalt pavement is removed to a specified depth and the surface is restored to

a desired grade cross slope and free of humps, ruts and other imperfections. The pavement


removal or “milling” is completed with a self propelled rotary drum cold planing machine. The

Reclaimed Asphalt Pavement (RAP) is transferred to trucks after removal and stockpiled for hot or

cold recycling.

Hot recycling:-RAP is combined with new aggregate and asphalt cement and/or recycling agent to

produce Hot Mix Asphalt (HMA). Although batch type hot mix plants are used, drum plants

typically are used to produce the recycled mix. Most of the RAP is produced by cold planing but

also can be produced from pavement removal and crushing. The mix placement and compacting

equipment and procedures are those typical of HMA construction.

Hot In-place Recycling (HIPR): The HIPR is defined as a process to correct asphalt pavement

surface distress by softening the existing surface with heat, mechanically removing the pavement

surface, mixing the reclaimed asphalt with a recycling agent, possibly adding virgin asphalt and/or

aggregate, and relaying. A train of machines, working in succession, performs the recycling.

Cold Recycling:- Although cold recycling is performed using a stationary or mobile plant process,

the method most commonly used is Cold In-place Recycling (CIR). For CIR, the existing asphalt

pavement typically is processes to a depth of from 50 to 100mm. the pavement is pulverized and

the reclaimed material is mixed with an Emulsion or foamed bitumen, spread and compacted to

produce a base course. Cold recycled base courses require a new asphalt surface

Full Depth Reclamation (FDR):- With FDR, all of the pavement section, and in some cases a

predetermined amount of underlying material are mixed with asphalt emulsion or Foamed bitumen

to produce a stabilized base course. Base problems can be corrected with this construction. FDR

consists of six basic steps: pulverization, stabilizing agent and/or emulsion or Foamed bitumen

incorporation, spreading, compacting, shaping and placement of new asphalt surface. [2]

2.4 Candidates for Recycling A candidate for recycling is usually an old asphalt pavement, from HMA to an aggregate base

with surface treatment. Candidate pavement will have severe cracking and disintegration, such as

pot holes. Frequently the poor condition is due to the pavement being too thin or weak for the

traffic and so it is being over stressed. Poor drainage can also accelerate the rate and amount of

pavement deterioration. All types of asphalt pavements can be recycled: low, medium and high

traffic volume highways, urban streets, airport taxi ways, runways and aprons, and parking lots.

[2]


2.5 Advantages of Cold Recycling Cold recycling and full depth reclamation of asphalt pavements provide many environmental and

other advantages:

Energy is conserved as the construction is completed in-place/mobile plant and no fuel is

required for aggregate heating.

Reflective cracking can be controlled since it is normally reduced with CIR and eliminated

by Full Depth Reclamation

Pavement crown and cross slope can be improved or restored.

Pavement maintenance costs can be reduced by increasing Life Cycle Cost of the existing

materials since it is reclaimed.

Traffic can be allowed immediately after construction of the pavement and the obstructions

to the traffic are also nominal since the construction operation can be carried out safely.

Existing material can be used completely (100% usage) irrespective of material quality.


2.6 Bitumen Emulsion Bitumen emulsions, used in road construction and maintenance, may be defined as a homogeneous

mixture of minute Bitumen droplets suspended in a continuous water phase. These types of

emulsions are usually termed oil-in-water (o/w) emulsions. Emulsions typically contain asphalt

cement, water, and emulsifying agent in the following approximate proportions: 65-70%, 30-35%,

and 2-3%, respectively. Their preparation involves the use of a high speed, high shear mechanical

device, such as a colloid mill. The colloid mill breaks down molten asphalt into minute droplets in

the presence of water and a chemical, surface-active emulsifier. The emulsifier imparts its

properties to the dispersed asphalt arid is most influential in maintaining stable asphalt droplet

suspension.

Advantages of emulsion:

The emulsions are more tolerant than penetration grade bitumens, of the presence of

dampness, although they should not be used in the presence of free water, on the road

surface or on aggregates.

Because emulsions are of relatively low viscous at normal temperatures, they eliminate the

need to heat the aggregates and binder, and thus they conserve energy.

Emulsions use reduces environmental pollution (especially because, unlike cutback

bitumen, they do not release harmful diluents in to the environment).

They can be used when the weather is relatively cold.

Table2. 10: The major uses of bitumen emulsion Surface treatments Asphalt recycling Other applications Fog sealing, Sand sealing, Slurry sealing, Micro-surfacing, Cape sealing

Cold in-place, Full depth, Hot in-place, Central plant

Stabilization, Maintenance patching, Tack coats, Prime coats, Dust palliatives, Crack filling, Protective coatings


2.7 Bitumen Emulsion Classification Bitumen emulsions are classified into three categories: anionic, cationic and nonionic. In practice

the first two types are more widely used in roadway construction and maintenance.

Emulsions are further classified on the basis of how quickly the bitumen droplets will coalesce.

The terms RS, MS, SS and QS have been adopted in this classification. They are relative terms

only and mean rapid setting, medium setting, slow setting and quick setting. The tendency to

coalesce is closely related to the speed with which an emulsion will become un-stable and break

after contacting the surface of aggregate. An RS emulsion has little or no ability to mix with an

aggregate, an MS emulsion is expected to mix with coarse but not fine aggregate, and SS and QS

emulsions are designed to mix with fine aggregate, with the QS expected to break more quickly

than the SS.

Emulsions are further identified by a series of numbers and letters related to viscosity of the

emulsions and hardness of the base bitumen. The letter “C” in front of the emulsion type denotes

cationic. The absence of “C” denotes anionic in American Society for Testing and Materials

(ASTM) and American Association of State Highway and Transportation Officials (AASHTO)

specifications.

The numbers in the classification indicate the relative viscosity of the emulsion. For example, an

MS-2 is more viscous than an MS-1. The “h” that fallows certain grades simply means that harder

base bitumen is used. An “s” means that softer base bitumen is used.

The “HF” preceding some of the anionic grades indicates high-float, as measured by the float test.

High float emulsions have a gel quality, imparted by the addition of certain chemicals, that permits

a thicker bitumen film on the aggregate particles and prevents drain off of bitumen from the

aggregate. These grades are primarily for cold and hot plant mixes, seal coats and road mixes.[6]

Table2. 11: Bitumen emulsion classification and their recommended application. (IS 8887-2004) Emulsion

type Recommended application

RS-1 Tack coat applications. RS-2 Surface dressing work.

MS Plant or road mixes with coarse aggregates minimum 80%, all of which is retained on 2.36mm IS Sieve, and also for surface dressing and penetration macadam.

SS-1 Fog seal, Crack sealing and Prime coat applications.

SS-2 Plant or road mixes with graded and fine aggregates such as Cold mixes MSS, SDBC and slurry seal.


2.8 Recycling With Bitumen Emulsion When recycling with bitumen emulsion the following points are important and need to be

addressed:

Mix design

As with any form of stabilisation, a proper mix design procedure should be followed to determine

the correct application rate required to meet the strength criteria. Each material requires its own

application rate of bitumen emulsion to achieve optimum or desired strength.

Formulation

Different emulsifiers and additives are used in varying proportions to “tailor” an emulsion for a

specific application. In addition to determining the amount of residual bitumen suspended in

water, such tailoring is aimed at controlling the conditions under which the bitumen breaks. Since

the type of material that is mixed with the emulsion has a major influence on stability (breaking-

time), it is important that the manufacturer be given a representative sample of the material that is

to be recycled. Details of any active filler to be added in conjunction with the bitumen emulsion

must also be supplied to allow the correct formulation to be developed and tested.

Handling

Bitumen emulsions are susceptible to temperature and pressure. The conditions that will promote

the bitumen to separate out of suspension (slowly as “flocculation”, or instantly as a “flash-break”)

must be clearly understood to prevent this from happening on the site. Likewise, the manufacturer

must know the conditions prevailing on site to allow the correct formulation, including the details

of all pumps that will be used for transferring the emulsion between tankers and for supplying the

spray bar on the recycler. Blending of anionic and cationic emulsions results in an instantaneous

break and blockage of pumps and pipes with viscous bitumen, for example. This can be prevented

by labeling and storing emulsions carefully and ensuring that distribution systems are clear of

residue from previous use.

Total fluid content concept

When working with bitumen emulsions, “Total Fluid Content” is used in place of Moisture

Content in defining the moisture/density relationship. Maximum density is achieved at the

Optimum Total Fluid Content (OTFC), which is the combined mass of moisture and bitumen

emulsion in the mix. Before breaking, bitumen emulsion is a fluid with a viscosity slightly higher


than that of water. Both the bitumen and water components of an emulsion act as a lubricant in

assisting compaction, so both must be included as fluids. This is illustrated in Figure 2-1.

Figure 2-1 Example of fluid considerations for a bitumen emulsion stabilised material

The example in Figure 2-1 shows the in-situ field moisture content as 2.5 % with 3.5 % bitumen

emulsion applied whilst recycling. The material has an OTFC of 7% under standard compaction.

An additional 1.0% of water may be added during recycling to bring the total fluid content to the

OTFC, or additional compactive effort applied to achieve maximum density. If the total fluid

content of the material approaches saturation level (as indicated by the zero air voids line), then

hydraulic pressures will develop under the roller causing the material to heave. When such

conditions arise it is impossible to compact the material. Where the in-situ field moisture content

is high (i.e. approaching the OTFC), the addition of bitumen emulsion can increase the total fluid

content beyond the saturation point. This situation cannot be addressed by reducing the amount of

bitumen emulsion added without compromising the quality of the stabilised product. The

temptation to add cement to the mix in order to “absorb the surplus moisture” should not be

considered since such a practice introduces rigidity and changes the nature of the product. High in-


situ moisture contents are best addressed by pre-pulverising the existing pavement thereby

exposing the material and allowing it to dry sufficiently before stabilising.

Processing time

No specific time limit is placed on working with bitumen emulsions other than the requirement of

completing all processing, compacting and finishing before the emulsion breaks. When emulsion

breaks, the bitumen comes out of suspension and the viscosity of the fluid increases significantly.

The individual particles of the recycled material will then be either coated, or semi-coated with a

thin film of cold, viscous bitumen, making it more difficult to compact. Compaction should

therefore be completed before or during the emulsion breaking process.

Density

The compaction should always aim to achieve the maximum density possible under the conditions

prevailing on site (the so-called “refusal density”). A minimum density is usually specified as a

percentage of the modified AASHTO density, normally between 98 and 102% for bitumen

stabilised bases.

Quality control

Briquettes (for strength testing) are normally manufactured from samples taken immediately

behind the recycler. These briquettes must be made before the emulsion breaks, thereby obtaining

specimens that reflect the compacted material on the road. Often the only way that this can be

achieved is by having a mobile compaction facility on site to manufacture the briquettes.

Alternatively, cores can be extracted at a later date once the layer has fully cured.

Curing

In order to gain strength, an emulsion mix must dispel excess water, or cure. Although some

materials stabilised with bitumen emulsion may achieve their full strength within a short period of

time (one month), curing can take longer than a year with other materials. The length of this

period is affected by field moisture content, emulsion/aggregate interaction, local climate

(temperature, precipitation and humidity) and voids in the mix. Cement addition has a significant

impact on the rate of gain of strength. This is particularly useful where traffic is to be

accommodated on a recycled layer shortly after treatment, Research, however, has shown that

adding more than 2% by mass negatively affects the fatigue properties of the stabilised layer. For

this reason the application rate of cement is usually limited to preferably 1.5% maximum but an

absolute maximum of 2%.


2.9 Foamed Bitumen In order to mix bitumen with road-building aggregates, you first need to considerably reduce the

viscosity of the cold hard binder. Traditionally, this was done by heating the bitumen and mixing

it with heated aggregates to produce hot mix asphalt. Other methods of reducing the bitumen

viscosity include dissolving the bitumen in solvents and emulsification. Prof. Csanyi came up

with the idea of introducing moisture into a stream of hot bitumen, which effects a spontaneous

foaming of the bitumen (similar to spilling water into hot oil). The potential of foamed bitumen for

use as a binder was first realised in 1956 by Dr. Ladis H. Csanyi, at the Engineering Experiment

Station in Iowa State University. Since then, foamed asphalt technology has been used

successfully in many countries, with corresponding evolution of the original bitumen foaming

process as experience was gained in its use. The original process consisted of injecting steam into

hot bitumen. The steam foaming system was very convenient for asphalt plants where steam was

readily available but it proved to be impractical for in situ foaming operations, because of the need

for special equipment such as steam boilers. In 1968, Mobil Oil Australia, which had acquired the

patent rights for Csanyi’s invention, modified the original process by adding cold water rather than

steam into the hot bitumen. The bitumen foaming process thus became much more practical and

economical for general use.[4]

Figure 2-2 schematic diagram of foamed bitumen production

The foamed bitumen, or expanded bitumen, is produced by a process in which pressurized water

and compressed air is injected into the hot bitumen (155-180 0c), resulting in spontaneous

foaming. The physical properties of the bitumen are temporarily altered when the injected water,


on contact with the hot bitumen, is turned into vapour which is trapped in thousands of tiny

bitumen bubbles. In the foam state the bitumen has a very large surface area and extremely low

viscosity making it ideal for mixing with aggregates however the foam dissipates in less than a

minute and the bitumen resumes its original properties. In order to produce foamed asphalt mix,

the bitumen has to be incorporated into the aggregates while still in its foamed state. A distinct

difference between foamed asphalt mixes and conventional asphalt stabilised mixes is the way in

which the bitumen is dispersed through the aggregate. In the later case the bitumen tends to coat

all particles whilst in the foamed mixes the larger particles are not fully coated. The foamed

bitumen disperses itself among the finer particles forming a mortar which binds the mix together.

Foamed bitumen mixes can achieve stiffness close to those of cement treated bases (3000 MPa)

but remains flexible like asphalt mix.[5]

2.10 Characterization of Foamed Bitumen Foamed bitumen is characterized by two primary properties:

1. Expansion Ratio that is a measure of the viscosity of the foam and will determine how

well it will disperse in the mix. It is calculated as the ratio of the maximum volume of

foam relative to its original volume or

Foam ratio, it is calculated as the maximum expanded volume of bitumen foam to its

weight and

2. Half-Life is a measure of the stability of the foam and provides an indication of the rate of

collapse of the foam. It is calculated as the time taken in seconds for the foam to collapse

to half of its maximum volume.

The “best” foam is generally considered to be the one that optimizes both expansion and half-life.


Figure 2-3: Bitumen Foam characterization

2.11 Factors influencing foam properties The expansion ratio and half-life of foamed bitumen is influenced by:

Water addition: Increasing the amount of water injected into the bitumen effectively increases the

volume of foam produced by a 1500 times multiplier. Thus, increasing the amount of water

increases the size of the bubbles created, causing the expansion ratio to increase. However,

increasing the size of the individual bubbles reduces the film thickness of the surrounding

bitumen, making it less stable and resulting in a reduction in half-life. Hence, the expansion ratio

and half-life are inversely related to the amount of water that is added,

Bitumen type: Bitumens with penetration values between 80 and 150 are generally used for

foaming, although harder bitumens that meet the minimum foaming requirements (explained

below) have been successfully used in the past. For practical reasons, harder bitumens are

generally avoided as they produce poorer quality foam, leading to poorer dispersion.


Bitumen source: Some bitumens foam better than others due to their composition. For example,

the foaming properties of bitumens from Venezuela far exceed those from most other sources.

Bitumen temperature: The viscosity of bitumen enjoys an inverse relationship with temperature;

as the temperature increases, its viscosity reduces. Logically, the lower the viscosity, the bigger

the size of bubble that will form when the water changes state in the foaming process. Since this

process draws heat energy from the bitumen, the temperature before foaming needs to exceed 160

ºC to achieve a satisfactory product.

Bitumen and water pressure: Bitumen and water are injected into the expansion chamber through

small diameter openings. Increasing the pressure in the supply lines causes the flow through these

openings to disperse (atomize). The smaller the individual particles, the larger the contact area

available, thereby improving the uniformity of the foam;

Additives: There are numerous proprietary products on the market that will affect the foaming

properties of bitumen, both negatively (anti-foaming agents) and positively (foamants). Foamants

are usually only required where bitumen has been treated with an anti-foaming agent (normally

during refining process). Most foamants are added to the bitumen prior to heating to application

temperatures and tend to be heat-sensitive; implying that their effect is short lived. To reap the

benefits of adding a foamant, the bitumen must therefore be used within a few hours. However,

these products are generally expensive and are usually only considered as a last resort to

improving the foaming properties of stubborn bitumen. (Cutting back the bitumen with diesel oil

has proved successful in reducing the viscosity of the bitumen sufficiently to achieve acceptable

foam. However, this is not recommended unless carried out by the bitumen supplier.)

Acceptable foaming characteristics

The bitumen intended to be used for foaming should be tested in the laboratory to determine the

foaming characteristics. The objective of this exercise is to find that combination of water addition

and bitumen temperature at which the optimal foam (highest Expansion Ratio and Half-Life) is

achieved. As described above, every bitumen is different and even different batches of bitumen

from the same source will vary. However, by following the simple laboratory procedure, the water

application and bitumen temperature is determined for each bitumen and these are then used on

site for full-scale foamed bitumen stabilisation. There are no upper limits to foaming

characteristics and the aim should always be to produce the best quality foam for stabilisation.

Problems are only encountered when a bitumen fails to produce a “good” foam, necessitating that


lower limits be recognized. Normally accepted minimum values for expansion ratio and half-life

for stabilising material at 25 ºC are:

Expansion Ratio 10 times and Half-Life 8 seconds.

Experience has shown that adequate foam dispersion and effective stabilisation is possible

when the expansion ratio is as low as 8 times and the half-life is only 6 seconds. However,

factors other than the foaming characteristics are often responsible, such as elevated material

temperatures. During his research into foamed bitumen during the late 1990s, Prof. Jenkins

developed the concept of a “Foam Index” to measure the combination of expansion ratio and half-

life. He defined this Foam Index as the area under the curve obtained by plotting Expansion Ratio

against Half-life, concluding that the better the foaming properties, the greater the Foam Index and

the better the stabilised product achieved. His research went on to compare the effect of Foam

Index with the temperature of the material at the time of mixing, concluding that as the

temperature of material increases, a lower Foam Index can be used to achieve effective

stabilization.[7]

2.12 Dispersion of foamed bitumen Unlike hot-mix asphalt, material stabilised with foamed bitumen does not appear black. This

results from the coarser particles of aggregate not being coated with bitumen. When foamed

bitumen comes into contact with aggregate, the bitumen bubbles burst into millions of tiny

bitumen droplets that seek out and adhere to the fine particles, specifically the fraction smaller

than 0.075 mm. The bitumen droplets can exchange heat only with the filler fraction and still have

sufficiently low viscosity to coat the particles. The foamed mix results in a bitumen-bound filler

that acts as a mortar between the coarse particles, as shown previously in Figure 4.1. There is

therefore only a slight darkening in the color of the material after treatment. The addition of

cement, lime or other such fine cementitious material (100 % passing the 0.075 mm sieve) assists

the bitumen to disperse, in particular where the recycled material is deficient in fines.


Figure 2-4: Foamed bitumen dispersion and binding in the treated mix

2.13 Material suitability for foamed bitumen treatment The foamed bitumen process is suitable for treating a wide range of materials, ranging from sands,

through weathered gravels to crushed stone and RAP. Aggregates of sound and marginal quality,

from both virgin and recycled sources have been successfully utilized in the process in the past. It

is important, however, to establish the boundaries of aggregate acceptability, as well as to identify

the optimal aggregate composition for foamed bitumen mix production. Material that is deficient

in fines will not mix well with foamed bitumen. As depicted in Figure 4.11, the minimum

requirement is 5% passing the 0.075 mm (No. 200) sieve. When a material has insufficient fines,

the foamed bitumen does not disperse properly and tends to form what are known as “stringers”

(bitumen rich agglomerations of fine material) throughout the recycled material. These stringers

vary in size according to the fines deficiency, a large deficiency will result in many large stringers

which will tend to act as a lubricant in the mix and lead to a reduction in strength and stability.


Figure 2-5: Material gradation envelops

Simple laboratory gradation tests carried out on representative samples taken from the existing

road will indicate any potential deficiency in the fines content. This can be rectified by importing a

suitable fine material and spreading on the road surface prior to recycling. Cohesive materials

should, however, be treated with care as standard laboratory gradings will indicate a high

percentage passing the 0.075 mm sieve, whilst in the field the quality of mixing is often poor. This

is due to the cohesive nature of the material causing the fines to bind together, thereby making

them unavailable to disperse the foamed bitumen. Comparison of washed and unwashed grading

tests carried out in the laboratory will indicate the likelihood of this problem developing, the

unwashed grading giving an indication of the available fines. Material that is deficient in fines can

be improved by the addition of cement, lime or other such material with 100 % passing the 0.075

mm sieve. However, the use of cement in excess of 1.5 % by mass should be avoided due to the

negative effect on the flexibility of the stabilised layer. The envelopes provided in Figure 2.5 are

broad and can be refined by targeting a grading that provides the lowest voids in the mineral

aggregate. This produces foamed bitumen mixes with the most desirable mix properties. A unique

relationship for achieving the minimum voids, with an allowance for variation in the filler content,

is shown in equation. This relationship is useful as it provides flexibility with the filler content of a

mixture. A value of n = 0.45 is utilised to achieve the minimum voids.

Where: d = selected sieve size (mm)


P = percentage by mass passing a sieve of size d (mm)

D = maximum aggregate size (mm)

F = percentage filler content (inert and active)

n = variable dependent on aggregate packing characteristics (0.45)

Achieving a continuous grading on the fraction less than 2 mm is important for the proper

dispersion of the foamed bitumen and easier compaction, thereby reducing voids and the

material’s susceptibility to water ingress. Where necessary, therefore, consideration should be

given to blending two materials to improve the critical grading characteristics.

2.14 Recycling with foamed bitumen Points to be considered while treating with Foamed bitumen Material temperature

Aggregate temperature is one of the primary factors influencing the successful dispersion of

foamed bitumen and, consequently, the strength achieved in the new pavement layer. As

mentioned above, the Foam Index concept developed by Prof. Jenkins represents the combined

foaming properties of bitumen (expansion ratio and half-life). His research finding showed that the

Foam Index and aggregate temperature (at the time of mixing) were important factors in the

dispersion achieved. Higher Foam Indices (i.e. better expansion and half-life) are necessary for

achieving a satisfactory mix at lower temperatures. Although the implications of these findings are

significant, it is important to compare laboratory conditions to those encountered in the field. The

quality of foam produced by a laboratory unit is always inferior to that produced by a large

recycler, the major reasons being higher working pressures in the field and continuity of operation

allowing the system to function at higher temperatures. There is therefore a shift between

laboratory and field measurements and, for this reason, it is important to check the foaming

properties in the field. These measurements should then be compared with the temperature of the

aggregate (not the road surface) and the results checked with the guidelines in Table. When the

temperature of the aggregate drops below 10 °C, foamed bitumen treatment should not be

considered.


Table2. 12: Foamed bitumen dispersion (ability to mix)

Consistency of bitumen supply

When coupling a new tanker to the recycler, two basic checks should be conducted to ensure that

the bitumen is acceptable for foaming:

– The temperature of the bitumen in the tanker should be checked using a calibrated thermometer

(gauges fitted to tankers are notoriously unreliable); and

– The foaming quality should be checked using the test nozzle on the recycler. This check should

be delayed until at least 100 liters of bitumen has passed through the spraybar whilst recycling in

order to obtain a truly representative sample.

Bitumen flow

Bitumen delivered to site by tankers that are fitted with fire-heated flues is sometimes

contaminated with small pieces of carbon that form on the sides of the flues whilst heating.

Draining the last few tons from the tanker tends to draw these unwanted particles into the

recycler’s system and can cause blockages. This problem is easily resolved by ensuring the

effectiveness of the filter in the delivery line. Any unusual increase in pressure will indicate that

the filter requires cleaning, a procedure that should anyway be undertaken on a regular basis (e.g.

at the end of every shift).

Bitumen pressure

The quality of foam is a function of bitumen operating pressure. The higher the pressure, the more

the stream of bitumen will tend to “atomise” as it passes through the jet into the expansion

chamber. This ensures that small bitumen particles will come in contact with the water that

similarly enters the expansion chamber in an atomised form, thereby promoting uniformity of

foam. If the bitumen were to enter the expansion chamber as a stream (as it does under low

pressures) the water would impact on only one side of the stream, creating foam, but the other side

would remain as unfoamed hot bitumen. It is therefore imperative to maintain a minimum

operating pressure above 3 bars.


Application of active filler

As described above, it is standard practice to add a small amount of cement or other such

cementitious stabilising agent when recycling with foamed bitumen. Care should be taken when

pre-treating with cement since the hydration process commences as soon as the dry powder comes

into contact with moisture, binding the fines and effectively reducing the 0.075 mm fraction. The

quality of the mix when foamed bitumen is subsequently added will be poor due to insufficient

fines being available to disperse the bitumen particles. Cement should therefore always be added

in conjunction with the foamed bitumen.

Table2. 13: Typical foamed bitumen contents relative to key aggregate fractions Percent passing

4.75 mm 0.075 mm Foamed bitumen content, %

3 – 5 3

5 – 7.5 3.5

7.5 – 10 4 < 50 (Gravel)

> 10 4.5

3 – 5 3.5

5 – 7.5 4

7.5 – 10 4.5 > 50 (Sands)

> 10 5

Table2. 14: Tentative binder and additional treatment requirements Material type

Optimum range of

binder

Additional requirements

Well graded clean gravel 2 to 2.5%

Well graded marginally clayey/silty

gravel

2 to 4.5%

Poorly graded marginally clayey gravel 2.5 to 3%

Clayey gravel 4 to 6% Lime modification

Well graded clean sand 4 to 5% Filler

Well graded marginally silty sand 2.5 to 4%

Poorly graded marginally silty sand 3 to 4.5% Low penetration bitumen,


filler

Poorly graded clean sand 2.5 to 5% filler

Silty sand 2.5 to 4.5%

Silty clayey sand 4% Possibly lime

Clayey sand 3 to 4% Lime modification

Moisture Conditions The moisture content during mixing and compaction is considered by many researchers to be the

most important mix design criteria for foamed asphalt mixes. Moisture is required to soften and

breakdown agglomerations in the aggregates, to aid in bitumen dispersion during mixing and for

field compaction. Insufficient water reduces the workability of the mix and results in inadequate

dispersion of the binder, while too much water lengthens the curing time, reduces the strength and

density of the compacted mix and may reduce the coating of the aggregates. The optimum

moisture content (OMC) varies, depending on the mix property that is being optimized (strength,

density, water absorption, swelling). However, since moisture is critical for mixing and

compaction, these operations should be considered when optimizing the moisture content.

Investigations by Mobil Oil suggest that the optimum moisture content for mixing lies at the “fluff

point” of the aggregate, i.e. the moisture content at which the aggregates have a maximum loose

bulk volume (70 % - 80 % mod AASHTO OMC) . However, the fluff point may be too low to

ensure adequate mixing (foam dispersion) and compaction, especially for finer materials. The

optimum mixing moisture content occurs in the range of 65 - 85 per cent of the modified

AASHTO OMC for the aggregates. The concept of optimum fluid content as used in granular

emulsion mixes may also be relevant to foamed asphalt. This concept considers the lubricating

action of the binder in addition to that of the moisture. Thus the actual moisture content of the mix

for optimum compaction is reduced in proportion to the amount of binder incorporated. The best

compactive moisture condition occurs when the total fluid content (moisture + bitumen) is

approximately equal to the OMC. [4]

Processing time No specific time limit is placed on working with foamed bitumen. Provided the moisture content

of the material is maintained close to the optimum moisture content, the working period can be

extended.

Curing Conditions


Studies have shown that foamed asphalt mixes do not develop their full strength after compaction

until a large percentage of the mixing moisture is lost. This process is termed curing. Curing is the

process whereby the foamed asphalt gradually gains strength over time accompanied by a

reduction in the moisture content. A laboratory mix design procedure would need to simulate the

field curing process in order to correlate the properties of laboratory- prepared mixes with those of

field mixes. Since the curing of foamed asphalt mixes in the field occurs over several months, it is

impractical to reproduce actual field curing conditions in the laboratory. An accelerated laboratory

curing procedure is required, in which the strength gain characteristics can be correlated with field

behaviour, especially with the early, intermediate and ultimate strengths attained. This

characterization is especially important and required when structural capacity analysis is based on

laboratory-measured strength values. Most of the previous investigations have adopted the

laboratory curing procedure proposed by Bowering (1970), i.e. 3 days oven curing at a temperature

of 60° C. This procedure results in the moisture content stabilizing at about 0 to 4 per cent, which

represents the driest state achievable in the field. In the present study the specimen are cured for 72

hours at 40 0C temperature only.

Density Generally density increases to a maximum and decreases as the binder content of a foamed asphalt

mix increases. The strength of foamed asphalt mixes depends to a large extent on the density of

the compacted mix. Compaction should always aim to achieve the maximum density possible

under the conditions prevailing on site (the so-called “refusal density”). A minimum density is

usually specified as a percentage of the modified AASHTO density, normally between 98 % and

102 % for foamed bitumen stabilised bases. A density gradient is sometimes permitted by

specifying an “average” density. This means that the density at the top of the layer may be higher

than at the bottom. Where specified, it is normal also to include a maximum deviation of 2% for

the density measured in the lowest one-third thickness of the layer. Hence, if the average density

specified is 100%, then the density at the bottom of the layer must be more then 98 %. For better

quality aggregates (e.g. CBR > 80 %) it is advisable to use an absolute density specification such

as Bulk Relative Density or Apparent Relative Density of the aggregate.

Engineering Properties The results of previous studies all confirm that strength parameters such as Resilient Modulus,

CBR and stability are optimized at a particular intermediate binder content. The most common

method used in the selection of the design binder content was to optimize the Marshall stability and


minimize the loss in stability under soaked moisture conditions. The major functions of foamed

bitumen treatment are to reduce the moisture susceptibility, to increase fatigue resistance and to

increase the cohesion of the untreated aggregate to acceptable levels. The design foamed bitumen

content could also be selected as the minimum (not necessarily optimum) amount of binder which

would result in a suitable mix.

Moisture Susceptibility

The strength characteristics of foamed asphalt mixes are highly moisture-dependent at low binder

contents. Additives such as lime or Cement reduced the moisture susceptibility of the mixes.

Higher bitumen contents also reduce moisture susceptibility because higher densities are

achievable, leading to lower permeabilities (lower void contents), and to increased coating of the

moisture-sensitive fines with binder. The moisture susceptibility of the material is usually

determined in terms of the Tensile Strength Retained (TSR) by 100 mm briquettes, using below

equation.

Temperature Susceptibility

Foamed asphalt mixes are not as temperature-susceptible as hot-mix asphalt, although both the

tensile strength and modulus of the former decrease with increasing temperature. Bissada (1987)

found that, at temperatures above 30° C, foamed asphalt mixes had higher moduli than equivalent

hot-mix asphalt mixes after 21 days’ curing at ambient temperatures. In foamed asphalt, since the

larger aggregates are not coated with binder, the friction between the aggregates is maintained at

higher temperatures. However the stability and viscosity of the bitumen-fines mortar will decrease

at high temperatures, thus accounting for the loss in strength.

Unconfined Compressive Strength (UCS) and Tensile Strength

Bowering (1970) suggested the following UCS criteria for foamed asphalt mixes used as a base

courses under thin surface treatments (seals): 0.5 MPa (4 day soaked) and 0.7 MPa (3 day cured at

60° C). Bowering and Martin (1976) suggested that in practice the UCS of foamed asphalt

materials usually lie in the range 1.8 MPa to 5.4 MPa and estimated that the tensile strengths of

foamed asphalt materials lay in the range 0.2 MPa to 0.55 MPa, depending on moisture condition.


Bitumen stabilised material is normally evaluated using the Indirect Tensile Strength (ITS) in

preference to Marshall testing with the fallowing advantages.

Simple to conduct the test

Specimen and the equipment are the same as those used for a Marshall testing machine.

The coefficient of variation of the test results is low as compared to other test methods and

This can be used to test under a static load i.e. a single load till failure.

For good performance, cured foamed asphalt samples should have minimum Indirect Tensile

Strengths of 100 kPa when tested in a soaked state and 200 kPa when tested dry.

Stiffness - Resilient Modulus

As with all viscoelastic bituminous materials, the stiffness of foamed asphalt depends on the

loading rate, stress level and temperature. Generally, stiffness has been shown to increase as the

fines content increases. In many cases the resilient moduli of foamed asphalt mixes have been

shown to be superior to those of equivalent hot-mix asphalt mixes at high temperatures (above 30°

C). Foamed asphalt can achieve stiffnesses comparable to those of cement-treated materials, with

the added advantages of flexibility and fatigue resistance.

Abrasion Resistance

Foamed asphalt mixes usually lack resistance to abrasion and ravelling and are not suitable for

wearing/friction course applications.

Fatigue Resistance

Fatigue resistance is an important factor in determining the structural capacity of foamed asphalt

pavement layers. Foamed asphalt mixes have mechanical characteristics that fall between those of

a granular structure and those of a cemented structure. Bissada (1987) considers that the fatigue

characteristics of foamed asphalt will thus be inferior to those of hot-mix asphalt materials. Little et

al (1983) provided evidence of this when he showed that certain foamed asphalt mixes exhibited

fatigue responses inferior to those of conventional hot-mix asphalt or high quality granular

emulsion mixes.


2.15 The benefits of foamed bitumen stabilisation

The following advantages of foamed asphalt are well documented:

• The foamed binder increases the shear strength and reduces the moisture susceptibility of

granular materials. The strength characteristics of foamed asphalt approach those of

cemented materials, but foamed asphalt is flexible and fatigue resistant.

• Foam treatment can be used with a wider range of aggregate types than other cold mix

processes.

• Reduced binder and transportation costs, as foamed asphalt requires less binder and water

than other types of cold mixing.

• Saving in time, because foamed asphalt can be compacted immediately and can carry

traffic almost immediately after compaction is completed.

• Energy conservation, because only the bitumen needs to be heated while the aggregates are

mixed in while cold and damp (no need for drying).

• Environmental side-effects resulting from the evaporation of volatiles from the mix are

avoided since curing does not result in the release of volatiles.

• Foamed asphalt can be stockpiled with no risk of binder runoff or leeching. Since foamed

asphalt remains workable for much extended periods, the usual time constraints for

achieving compaction, shaping and finishing of the layer are avoided.

• Foamed asphalt layers can be constructed even in some adverse weather conditions, such

as in cold weather or light rain, without significantly affecting the workability or the

quality of the finished layer.

The limitations are:

• Requires a suitable grading of fines in the pavement material

• Purpose built equipment and experienced operators are required

• A relative lack of abrasion resistance at surface and requires consideration of a good

surface course over the foamed bitumen treated layer.

Where would we consider this rehabilitation option?

This effective pavement rehabilitation option may be considered in most situations, such as:

• A pavement has been repeatedly patched to the extent that pavement repairs are no longer

cost effective;


• A weak granular base overlies a reasonably strong subgrade.

• A granular base too thin to consider using cementitious binders

• Conventional reseals or thin asphalt overlays can no longer correct flushing problems.

• An alternative to full-depth asphalt in moderate to high trafficked roads.

• Unfavorable wet cyclic conditions unsuitable for granular construction.

• Situations where an overlay is not possible due to site constraints e.g. entries to adjacent

properties & flood prone areas

• A requirement to complete the rehabilitation quickly to prevent disruption to business or

residents


Table2.15: Comparison between different types of bitumen applications Factor Bitumen Emulsion Foamed Bitumen Hot Mix Asphalt

Aggregate types

applicable

Crushed rock

Natural gravel

RAP, Cold mix

RAP, stabilised

Crushed rock

Natural gravel

RAP, stabilised

Marginal (Sands)

Crushed rock

0 to 50% RAP

Bitumen Mixing

Temperature

20 0C to 70 0C 160 0C to 180 0C

(Before foaming)

140 0C to 180 0C

Aggregate

temperature during

mixing

Ambient (cold) Ambient (cold) Hot only

(140 0C to 200 0C)

Moisture content

during mixing

90% of OMC minus

50% of emulsion

content

Below OMC

(e.g 65% to 95% of

OMC)

Dry

Type of coating of

aggregate

Partial coating of

coarse particles and

cohesion of mix with

bitumen / fines mortar

Coating of fine

particles only with

“spot welding” of mix

from the bitumen /

fines mortar

Coating of all

aggregate particles

with controlled film

thickness

Construction and

compaction

temperature

Ambient Ambient 140 0C to 160 0C

Rate of initial strength

gain

Slow Medium Fast

Modification of

binder

Yes Unsuitable Yes

Important parameters

of binder

Emulsion type

Residual bitumen

Breaking time

Curing

Half life

Expansion ratio

Penetration

Softening point

Viscosity


2.16 Case studies

Experience in India:

2.16.1 Emulsion Cold Recycling Rehabilitation Project-Hyderabad Project location Toli chowki area, Hydrabad

The road connecting Rethibowli and Gachibowli. The traffic made

up of cars, light vans, city buses and large delivery trucks.

Recycling method The rehabilitation method chosen for this road was Cold In Place

Recycling using an Emulsion as the binding agent. The Cold In-

Place Recycling option was chosen for the following reasons:

• Lower cost

• Ability to keep road open to business traffic

• Speed of operation

Road details Width of the road: 14m

Length of the road: 400m

Depth of the recycled layer: 120mm

Material composition RAP: 91%

Fine aggregate (P-2.36mm): 4%

Cement: 2%

Bitumen Emulsion: 3%;

Construction:

• Initially calculated amount of 2% of cement by weight of recycled mix was placed over the

road to be recycled. Later around 2% of fine aggregate passing 2.36mm was uniformly

spread over the section.

• With the help of recycler along with emulsion tanker the recycling job was carried out after

milling to a depth of 120mm of the existing surface while simultaneously mixing the

cement, emulsion (@ 3%), water and milled material to form a homogeneous mixture.

• The recycler is equipped with tamping screed, relayed the recycled material and at the

same time pre-compacted it.


• The laid recycled layer was compacted with a 15tonne vibratory roller. Initially high

amplitude and low frequency mode was selected and later after few passes the mode was

changed to low amplitude and high frequency so as to ensure proper compaction

throughout the recycled thickness.

• Next to rolling with the vibratory roller, a pneumatic tyred roller was used to complete the

final process of compaction.

• After one day water was sprinkled over the laid surface to enable proper curing.

• Later the road was opened to the traffic. However it was felt appropriate to provide a layer

of tack coat followed by a surface course of SDBC.


Figure2.6: A view of recycling process progress in Hyderabad

Figure2.7: Aggregate Spread over the layer to be recycled to correct the Gradation


Figure2.8: Recycling crew in action

Figure2.9: Recycled layer after pre-compaction


Figure2.10: Compacting the recycled layer

Figure2.11: Tack coat application over the recycled and compacted layer


Figure2.12: Finished surface of the recycled layer


2.16.2 Foam bitumen cold recycling rehabilitation project-Bangalore Existing Pavement

Kumbalgodu is an Industrial area, traffic made up of cars, light

vans and large delivery trucks. The road is 5m wide and average

asphalt thickness of 20mm.

Recycling Method In-Plant Cold Recycling

Project location Kumbalgodu industrial area phase-I, Bangalore.

A street road connecting state highway No:17 (Bangalore-Mysore)

and some industries (Pressman India Pvt. Ltd, Karnataka cold

storage Pvt. Ltd. etc.)

Road details Width of the road: 5m

Length of the road: 400m

Depth of the Recycled layer: 100mm

Material sourced from RAP material from BC layer of SH-17 from 31 km to 33 km.

Crusher Stone Dust from BIDADI village quarry located at

35+100 km of SH-17.

Bitumen used for foaming is of 80/100 penetration grade.

Material composition RAP: 75% by wt of aggregate;

Stone Dust: 25% by wt of aggregate

Cement: 1.5% by wt of aggregate;

Foamed bitumen: 3.5% by wt of mix;

Water: 3% by wt of mix

Construction:

• The road to be paved with plant recycled material was cleaned and sprinkled with water to

damp the surface to ensure proper bond.

• Foamed bituminous recycled mix was prepared in the mobile mixing plant (KMA-200)

using RAP, Stone dust, Cement and Foamed bitumen in formulated proportions just near

by the working site.

• Recycled plant mix was transported by dumper and is dumped in to the hopper of the paver

to lay the foamix.


• The compaction process was started with vibratory roller and is finished with pneumatic

tyred roller to achieve specified density and smooth finished surface.

• The recycled road surface was opened to the traffic after 12 hours of construction.

• Two coats of tack coat application and dust spreading was being carried out to seal the

surface in a gap of 4 days.


Figure2.13: Loader used to load the materials in to the mobile plant

Figure2.14: Cement and hot bitumen supplied to the plant


Figure2.15: Recycled material being discharged in to the dumper

Figure2.16: Recycled foamix being dumped in to the paver hopper


Figure2.17: Initial compaction with vibratory roller

Figure2.18: Final compaction with pneumatic tyred roller


Experience in abroad:

2.16.3 Emulsion Cold Recycling Rehabilitation Project. Citizen Court, Toronto, June 2003 Existing Pavement

Citizen Court is an Industrial area, traffic made up of cars, light

vans and large delivery trucks (Container type). The road is

10.4m wide with and average asphalt thickness of 90mm. The

existing pavement is 18 years old and has reached the end of it’s

useful life, distress is mainly localised base failure with alligator

cracking.

Rehabilitation Method:

The rehabilitation method chosen for Citizen Court was Cold In

Place Recycling using an Emulsion as the binding agent. The

Cold In-Place Recycling option was chosen for the following

reasons:

• Lower cost

• Ability to keep road open to business traffic

• Speed of operation

Design Mix:

Depth of cutting 80 mm

Grindings 98.40%

Emulsion 1.60%

Water Added 2.90% and

Finish Course 40 mm Asphalt concrete

Recycling Train The Recycling train consisted: Wirtgen 2200CR (fitted 2.5m

width milling drum), Emulsion Supply tanker. The Emulsion

Tanker is pushed by the Wirtgen 2200CR, the recycler therefore

controls the speed of operation, and the emulsion application rate

is proportional to recycler forward speed (Average speed 7.5m /

min.). The water for compaction is drawn from the 2200CR

onboard water tank, 5000 litre capacity. The Compaction

achieved using: Single steel drum vibratory compactor, followed

by Pneumatic Multi Tyred Compactor.


Recycling Sequence of Operation

Pass No 1:

2.5m wide, from centre line out. The total width of the pavement was 10.4m wide, 5.2m half

width. Maximum recycled width with 2 passes of the 2200CR (fitted with 2.5m cutter) was 4.9m,

allowing overlap of 0.1 m at the joint. Therefore, it was necessary to mill 0.5m width x 80mm

depth from kerb outwards, the milled material being windrowed to the side.

Pass No. 2:

The pre-milled material is incorporated into the 2200CR mixing drum, to be treated with

emulsion. Total recycled width after 2 passes 5.2m

Screed set up:

Pass No 1: The screed was set for 2.5m width to match the recycled width.

Pass No 2: The right hand section of the screed is set to 1.55m width, to match half the 2200CR

cutter width plus the pre milled section. The left hand screed width is set to 1.25m width, to match

half the 2200CR cutter width. Right hand screed section set to pave up to kerb edge. Total screed

width in Pass No. 2 is 2.8m.

Total 4 passes required for a 10.4m road width.


Figure2.19: Recycling option used

Figure 2-20: Emulsion tanker and recycler


Figure 2-21: Pre-compacted surface after 1st pass

Figure 2-22: Cold milling from kerb outwards


Figure 2-23: Pre-compacted surface after 2nd pass


2.16.4 Saudi Arabia – A desert road for heavy traffic The dual-lane Shaybah Access Road, with a total length of more than 380 km, leads from the

Batha main route to the Saudi Aramco Shaybah area in the Rub Al Khali desert. The construction

of a reliable traffic route was imperative for the development of an oil field with affiliated

refinery, and for the heavy-duty traffic to be expected in connection with the transport of

components for the processing plant weighing up to 200 t. Originally built from Marl as an

unbound gravel road only, the total length of the Shaybah Access Road was therefore recycled

within 180 days only using the foamed bitumen technology. During the main construction phase,

three Wirtgen Cold Recyclers WR 2500 and Mobile Slurry Mixing Plants WM 400 were in

operation on site. With the addition of 5% foamed bitumen and 2% cement slurry, a daily average

of approximately 35,000 m2 of existing pavement could be scarified and recycled with the binding

agents down to a depth of 20 cm. In order to optimise the workability and compaction properties

of the existing sub-base, which consisted of Marl and sand, approximately 4% water were added.

In addition to the Wirtgen machines WR 2500 and WM 400, motor graders as well as vibrating

rollers and pneumatic tired rollers were employed to profile and compact the treated material. In

order to ensure an optimum work pattern and to achieve the highest possible quality, two recycling

trains worked staggered behind one another, thus ensuring good adhesion between the individual

machine passes and an optimum profiling of the complete lane. This also enabled the heavy-duty

traffic to pass the ever moving job site during the whole duration of the rehabilitation project.

Finally, a bituminous surface treatment, in the form of a slurry seal, was applied on the recycled

base layer. In an inspection report, road construction experts praised the good suitability of foamed

bitumen as a stabilising agent even under these extreme climatic conditions, as well as its high

economic efficiency. The original plans involving conventional construction methods with

imported crushed aggregate and hot mix asphalt had been rejected as these would have met neither

the economical nor the time frame of this project. Figure 2-24 shows one of the three Wirtgen

recycling trains consisting of a WR 2500 and a Slurry Mixer WM 400 during the economical

rehabilitation of the Shaybah Access Road, In operation 24 hours a day despite extreme climatic

conditions.


Figure 2-24: Recycling of Shaybah Access road


2.16.5 In-Plant recycling using milled asphalt bound with foamed bitumen Responsible parties

Client: Durban Municipality, Roads Department - City Engineers Unit

Contractor: Milling Techniks

Design Engineers: Siyenza Engineers / Loudon International

Equipment suppliers: Wirtgen South Africa with Wirtgen GmbH (Germany)

Introduction

The Newlands West Drive, which serves as a mayor bus route and arterial to a large residential

area, showed signs of distress in the form of cracking of the existing asphalt layers. The

rehabilitation design called for an overlay on to the existing road of 125 mm thick foamed bitumen

stabilised RAP and 40 mm asphalt surfacing. The alternative conventional rehabilitation method

with the same structural capacity would have been to overlay the existing road with an 100 mm

asphalt binder layer and a 40 mm asphalt surfacing. Due to the increasing volume of stockpiled

RAP at the municipal depots and the relatively low stabilising agent contents required, the

alternative using the in-plant recycling method showed a significant saving for the client. This

project coincided with the 22nd PIARC World Road Congress. Thanks to the future orientated

thinking of the Durban Municipality, an agreement was reached together with Milling Techniks

and Wirtgen South Africa to showcase the in-plant recycling and foamed bitumen technology to

the international road construction industry attending the congress during the week of 20 . 24

October 2003.


Project details

Length of road: 1000 m, Width of road: 8 m

Aggregate: Reclaimed Asphalt Pavement (RAP) collected from

various milling contracts and stockpiled at the Durban City council’s

depot.

Stabilising agents: 2 % Foamed bitumen (80/100 penetration grade)

and 1 % cement (OPC)

Equipment utilized RAP sizing plant: Hartl PC 1270 I (Impact crusher)

Mixing Plant: Wirtgen KMA 200

Paving unit: Vögele Super 1800

Compactors: HAMM HD O70V double smooth drum with one

Vibratory and one Oscillation drum; and HAMM GRW 18

(pneumatic tyred roller)

Technical information

Design Life: 20 years

Structural capacity: 4,8 million ESALs (80 kN = 8 ton)

Mix properties: Indirect Tensile Strength (150 dia. briquette) > 150

KPa

Retained strength > 90 %

Unconfined Compressive Strength > 1500 KPa

Compaction: > 100 % of modified AASHTO density (1984 kg/m³)


Construction Method

A Hartl Power crusher PC 1270 impact crusher, was used to break down the oversized particles

within the RAP so that 100 % of the RAP could be utilized. This crushed material was then loaded

into the hopper of the Wirtgen KMA 200 by means of a Payloader. The KMA 200 cold mixing

plant was used to add the binding agents, being 2 % foamed bitumen, 1 % cement. In addition

1,5% to 2,0% water was added to achieve 90 % of the optimum moisture content. The cold mixed

material exiting out of the KMA 200 is loaded directly onto tip trucks and transported to

Newlands West drive, approximately 8 km away from the mixing plant area. The cold processed

material was then placed with a Vögele 1800 road paver. The TV screed on the paver equipped

with Tampers and Vibration achieved a very high degree of compaction. The layer thickness

directly behind the paving screed was 150 mm. To achieve the specified compaction (greater than

100 % of modified Proctor density) the rollers merely had to compact the material to a thickness

of 125 mm. The compaction was achieved with a HAMM HD 70 Oscillation tandem roller and a

HAMM GRW 18 pneumatic tyred roller. During final compaction a light spray of water was

applied. This resulted in a tight knit surface, which was resistant to the wear and tear of the traffic.

The foamed bitumen bound layer was trafficked immediately after final compaction was

completed. Before the second half was paved, the transverse tie-in joint was cut by means of a

grader. An alternative method of creating this tie-in joint would be by means of a W 350 milling

machine. The longitudinal joint was moistened by means of a water hosepipe and a water tanker. It

is the nature of the foamed bitumen material to be workable, even after many hours or even weeks

after mixing. Therefore the main advantages of using this cold treated material are that the layer

can be trafficking directly after compaction has been completed and because the entire process is a

cold process the cold joints merely need to be moistened to achieve good bonding. If the

transverse day joints and longitudinal construction joints are constructed as described, they are as

sound as the rest of the pavement. This is due to the nature of the foamed bitumen treated material,

i.e. bitumen rich mortar binding together the entire granular matrix, and the fact that particle

interlock is achieved. The finished cold recycled base course lay open without a wearing course

between 6 and 9 days, depending on the section. After this period a tack coat, using a stable 60

bitumen emulsion, was applied before a 4 cm Asphalt wearing course was paved.


Figure2-25: The Hartl Powercrusher PC 1270 I Impact crusher being used to crush the RAP

material.

Figure2-26: The Wirtgen KMA 200 cold mixing plant utilized to dose and mix the binding agents

and water with the RAP.


Figure 2-27: Vögele 1800 paving the foamed bitumen treated base material directly onto the road

as an overlay .

Figure 2-28: Compaction done with HAMM HD O70V double drum Oscillation / Vibration roller

and HAMM GRW 18 pneumatic tyred roller.


Figure2-29: The road surface being moistened with water during final compaction and just before

traffic is allowed onto the base course.

Figure2-30: The longitudinal joint being moistened before paving of the second road-width.


Figure 2-31: Paving of the second road width and traffic on the freshly compacted material. This

layer was kept moist for the first couple of hours for curing purposes.

Figure2-32: The finished cold recycled base course after being trafficked for several days.


Figure2-33: The Tack coat applied by a hand sprayer on one half of the base course.

Figure2-34: Paving and compaction of the 4 cm asphalt wearing course.


_________________________________________CHAPTER 3

3. LABORATORY AND FIELD STUDY

3.1 RAP and Mineral Aggregate Evaluation Representative sample of pulverized and air dried Reclaimed Asphalt Product (RAP) and Crusher

stone dust were collected from stock pile and then sieved through a set of sieves for gradation. The

details of sieve analysis are presented in tables 3.1 and 3.2. Bitumen content and moisture content

of air dried RAP found to be 5.2% and 0.12% respectively. Moisture content and specific gravity

of air dried Stone Dust found to be 0.40% and 2.68 respectively. Mineral fillers used in the present

study are hydrated lime of specific gravity 2.53, Ordinary Portland cement of 53-grade and Fly-

ash of specific gravity 2.12 (P-75µ=100%).

Table3. 7: Sieve analysis of pulverized and air-dried RAP sieve size,

mm 37.5 26.5 19 13.2 9.5 6.7 4.75 2.36 1.18 0.6 0.425 0.3 0.075 pan

cumulative % passing 100.0 99.2 95.0 74.7 52.1 39.1 29.1 16.6 7.5 5.3 3.4 2.0 0.2 0.0

Table3. 8: Sieve analysis of Stone Dust

sieve size, mm 6.7 4.75 2.36 1.18 0.6 0.425 0.3 0.075 pan cumulative % passing 100.00 93.40 72.00 50.60 43.60 35.80 26.20 9.00 0.00

3.2 Foamed Bitumen Characterization

The Study of foamed bitumen and its characterization wais carried out using Wirtgen Foam

bitumen Laboratory plant, WLB-10 (Figure 3.1). The Foamability and the variation of foam

characteristics viz. expansion ratio and half life time were observed at different air pressures,

temperatures and Bitumen water contents. Dip stick and stop watch were used to find foam

volume and half life. The height of foamed bitumen immediately after complete spray and after

complete foam collapse was found to determine the Expansion ratio. The discharging capacity of

bitumen pump found to be 125 grams/second and the injection time of foam adopted was

5seconds. The bitumen used was of 80/100 penetration grade. The graphs (figures 3.2, 3.3 and 3.3)

were plotted to determine the optimum foam producing air pressure, bitumen temperature, and

bitumen water content.

Study of Air pressure Influence on expansion ratio and half time of Foamed bitumen: The Bitumen water, 3% (i.e. Bitumen water discharge, 10.8 l/h) and Bitumen temperature, 165 0c

were kept constant and the air pressure was varied from 3 to 6 bars at an interval of 1 bar to study


the influence of air pressure. The bitumen water pressure was kept 1 bar more than the air pressure

as given in WLB-10 operation manual. Basic height of bitumen of 625 g per unit area of container

was found to be 1.2 cms after complete collapse of the foam. The graph plotted keeping air

pressure on X-axis and expansion ratio and half life were kept on Y-axis. From this study and

looking in to the figure 3.2 optimum Air pressure was decided as (3.85+4.8)/2 =4.325 bars,

fallowing the Minimum acceptable Bitumen foam parameters Expansion ratio 8 times and Half-

life time 6 seconds.

Study of Bitumen temperature Influence on expansion ratio and half time of Foamed bitumen

The Bitumen water, 3% (i.e. Bitumen water discharge, 10.8 l/h), Air pressure, 4.3 bars and

Bitumen water pressure, 5.3 bars were kept constant and Bitumen temperature was varied from

150 to 180 o C at an interval of 10 0C to study the variation of expansion ratio and half life time.

The graph plotted keeping Bitumen temperature on X-axis and expansion ratio and half life were

kept on Y-axis. From this study and looking in to the figure 3.3 optimum bitumen temperature was

decided as (154+156)/2 = 155 0C

Study of Bitumen water content Influence on expansion ratio and half life time of Foamed bitumen

The Air pressure, 4.3 bars, Bitumen water pressure, 5.3 bars and Bitumen temperature, 155 0C

were kept constant and Bitumen water content was varied from 8 to 15 liters per hour to study the

variation of expansion ratio and half life time. The graph plotted keeping Bitumen water content

on X-axis and expansion ratio and half life were kept on Y-axis. From this study and looking in to

the figure 3.4 optimum bitumen water content was decided as (2.7+3.8)/2=3.25 % of bitumen.

After studying the bitumen foam behaviour at different air pressures, temperatures and bitumen

water contents it is concluded to take optimum air pressure, temperature and bitumen water

contents as 4.3 bars, 155 to 160 0C and 12 l/h (i.e. 3.3% of bitumen) respectively to produce

acceptable bitumen foam and were fallowed while producing foamix.


Figure3. 5: WLB 10- Wirtgen foamed bitumen lab kit

Table3. 9: Air pressure Influence on expansion ratio and half time of Foamed bitumen

1st measurement

2nd measurement

3rd measurement

average value Air

pressure, bars

Maximum foam

height, in cm

Half life, s

Maximum foam

height, in cm

Half life, s

Maximum foam

height, in cm

Half life, s

Expansion ratio

Half life, s

3 8 8 10 7 9 8 7.50 7.67 4 9 7 9.5 8 8.5 8 7.50 7.67 5 11 5.5 13 5.5 11.5 5 9.86 5.33 6 12.5 4 13 4.5 12.5 5 10.56 4.50

3456789

101112

2.5 3 3.5 4 4.5 5 5.5 6 6.5Air pressure, bar

Expa

nsio

n ra

tio

0123456789

Hal

f life

, sec

onds

exp ratio

half life in seconds

Figure3. 6: Air pressure Influence on expansion ratio and half time of Foamed bitumen


Table3. 10: Bitumen temperature Influence on expansion ratio and half time of Foamed bitumen 1st measurement

2nd measurement

3rd measurement

average value

Bitumen

temparature,0C Maximum

foam height, in

cm

Half life, s

Maximum foam

height, in cm

Half life, s

Maximum foam

height, in cm

Half life, s Expansion ratio Half life, s

150 8 8 8.5 6 10 7.5 7.36 7.17 160 10 4 11 5.5 11 6 8.89 5.17 170 11 4.25 13 4.5 11.5 4.25 9.86 4.33 180 12.5 3.5 13 3.5 12 3 10.42 3.33

3456789

101112

145 150 155 160 165 170 175 180 185Temperature, 0C

Expa

nsio

n ra

tio

0123456789

Hal

f life

, sec

onds

exp ratio

half life in seconds

Figure3. 7: Bitumen temperature Influence on expansion ratio and half time of Foamed bitumen

Table3. 11: Study of Bitumen water content Influence on expansion ratio and half life time of Foamed bitumen

1st measurement

2nd measurement

3rd measurement

average value Bitumen

Water content,

%

Flow-through,

l/h

Maximum foam

height, in cm

Half life,

s

Maximum foam

height, in cm

Half life,

s

Maximum foam

height, in cm

Half life,

s

Expansion ratio

Half life, s

2.22 8 7 10 9.5 9.5 10.5 9 7.50 9.50 2.50 9 8.5 8 11.5 8 9.5 8 8.19 8.00 3.33 12 10 7 12 7 10.5 7 9.03 7.00 3.89 14 11 6 12.5 5.5 11 7.5 9.58 6.33 4.17 15 13.5 5 14 5 13.5 5 11.39 5.00


3456789

101112

2.0 2.5 3.0 3.5 4.0 4.5 Bitumen water content, %

Expa

nsio

n ra

tio

0123456789

Hal

f life

, sec

onds

exp ratio

half life

Figure3. 8: Bitumen water content Influence on expansion ratio and half life time of Foamed

bitumen

3.3 Emulsion Testing Table3. 12: Tests on Emulsion

Emulsion Property Observed value Specified value Residue on evaporation, Minimum % 66.5% 60% Viscosity, saybolt furol viscometer At 250C, seconds 48 30-150 Storage stability after 24 hours, Maximum 1.8% 2% Charge positive positive Miscibility with water No coagulation No coagulation Tests on residue: Penetration @250C, 100g, 5 seconds 85 60-120 Ductility @270C, cm, minimum 68 50

3.4 Mineral Aggregate Proportions Based on pulverized RAP and stone dust gradation their proportions were fixed to meet the

gradation requirement for Foamed bitumen treatment. Four different options of aggregate

proportions were chosen with different quantity of filler (table 3.7). And the same aggregate

proportions were fallowed for Emulsion treatment also. The details of aggregate proportions and

the gradation charts are given in Tables 3.8, 3.9, 3.10 and 3.11 and Figures 3.5, 3.6, 3.7 and 3.7

respectively.


Table3. 7: Different options of aggregate proportions RAP Stone Dust Filler Option: 1 54.00% 46.00% 0.00%

Option: 2 53.46% 45.55% 0.99% Option: 3 52.94% 45.10% 1.96%

Option: 4 52.40% 45.70% 2.90%

Table3. 8: Option1 Material proportions

Cumulative % passing Trials percentages specified limitssieve size, mm RAP SD RAP SD filler

combined grading upper lower

37.5 100 100 54.00 46.00 0.00 100.00 100.00 100.0026.5 99.24 100.00 53.59 46.00 0.00 99.59 100.00 85.37 19 95.02 100.00 51.31 46.00 0.00 97.31 100.00 73.33

13.2 74.72 100.00 40.35 46.00 0.00 86.35 86.81 62.07 9.5 52.12 100.00 28.14 46.00 0.00 74.14 76.63 53.37 6.7 39.17 100.00 21.15 46.00 0.00 67.15 67.34 45.44 4.75 29.10 93.40 15.71 42.96 0.00 58.68 59.52 38.75 2.36 16.66 72.00 9.00 33.12 0.00 42.12 46.89 27.97 1.18 7.58 50.60 4.09 23.28 0.00 27.37 37.75 20.16 0.6 5.32 43.60 2.87 20.06 0.00 22.93 31.20 14.56

0.425 3.46 35.80 1.87 16.47 0.00 18.34 28.55 12.30 0.3 2.03 26.20 1.09 12.05 0.00 13.15 26.26 10.35

0.075 0.25 9.00 0.14 4.14 0.00 4.28 20.00 5.00 Table3.9: Option2 Material proportions

Cumulative % passing Trials percentages specified

limits sieve size, mm RAP SD RAP SD filler


37.5 100 100 53.47 45.55 0.99 100.00 100 100 26.5 99.24 100.00 53.06 45.55 0.99 99.59 100 85 19 95.02 100.00 50.80 45.55 0.99 97.34 100 73

13.2 74.72 100.00 39.95 45.55 0.99 86.48 87 62 9.5 52.12 100.00 27.86 45.55 0.99 74.40 77 53 6.7 39.17 100.00 20.94 45.55 0.99 67.48 67 45 4.75 29.10 93.40 15.56 42.54 0.99 59.09 60 39 2.36 16.66 72.00 8.91 32.79 0.99 42.69 47 28 1.18 7.58 50.60 4.05 23.05 0.99 28.09 38 20 0.6 5.32 43.60 2.84 19.86 0.99 23.69 31 15

0.425 3.46 35.80 1.85 16.31 0.99 19.15 29 12 0.3 2.03 26.20 1.08 11.93 0.99 14.01 26 10

0.075 0.25 9.00 0.14 4.10 0.99 5.22 20 5


Table3.10: Option3 Material proportions Cumulative %

passing Trials percentages specified limits sieve size, mm

RAP SD RAP SD fillercombined grading

upper lower 37.5 100 100 52.94 45.10 1.96 100.00 100 100 26.5 99.24 100.00 52.54 45.10 1.96 99.60 100 85 19 95.02 100.00 50.31 45.10 1.96 97.36 100 73

13.2 74.72 100.00 39.56 45.10 1.96 86.61 87 62 9.5 52.12 100.00 27.59 45.10 1.96 74.65 77 53 6.7 39.17 100.00 20.74 45.10 1.96 67.80 67 45 4.75 29.10 93.40 15.40 42.12 1.96 59.49 60 39 2.36 16.66 72.00 8.82 32.47 1.96 43.25 47 28 1.18 7.58 50.60 4.01 22.82 1.96 28.79 38 20 0.6 5.32 43.60 2.81 19.66 1.96 24.44 31 15

0.425 3.46 35.80 1.83 16.15 1.96 19.94 29 12 0.3 2.03 26.20 1.07 11.82 1.96 14.85 26 10

0.075 0.25 9.00 0.13 4.06 1.96 6.15 20 5

Table3.11: Option4 Material proportions Cumulative %

passing Trials percentages specified

limits sieve size, mm RAP SD RAP SD filler


37.5 100 100 52.40 44.70 2.90 100.00 100 100 26.5 99.24 100.00 52.00 44.70 2.90 99.60 100 85 19 95.02 100.00 49.79 44.70 2.90 97.39 100 73

13.2 74.72 100.00 39.15 44.70 2.90 86.75 87 62 9.5 52.12 100.00 27.31 44.70 2.90 74.91 77 53 6.7 39.17 100.00 20.53 44.70 2.90 68.13 67 45 4.75 29.10 93.40 15.25 41.75 2.90 59.90 60 39 2.36 16.66 72.00 8.73 32.18 2.90 43.81 47 28 1.18 7.58 50.60 3.97 22.62 2.90 29.49 38 20 0.6 5.32 43.60 2.79 19.49 2.90 25.18 31 15

0.425 3.46 35.80 1.81 16.00 2.90 20.72 29 12 0.3 2.03 26.20 1.06 11.71 2.90 15.67 26 10

0.075 0.25 9.00 0.13 4.02 2.90 7.06 20 5


0

20

40

60

80

100

0.01 0.1 1 10 100

sieve size, mm (log scale)

Perc

ent

pass

ing

upper limitlower limit combinedRAPSD

Figure3. 5: option1 gradation curves

0

20

40

60

80

100

0.01 0.1 1 10 100sieve size, mm (log scale)

Perc

enta

ge p

assi

ng

lowerlimitupperlimitcombined achieved RAPstone dust



0

20

40

60

80

100


Perc

enta

ge p

assi

ng



0

20

40

60

80

100


Perc

enta

ge p

assi

ng




3.5 OMC Determination for Foamed Bitumen Treatment The pulverized and air dried RAP is separated in to three different fractions fallowing the

procedure described in Appendix A (i.e. P-19mm & R-13.2mm, P-13.2mm & R4.75mm and P-

4.75). The proportioned (Option 1) and un-treated material was used to find Optimum Moisture

Content with modified Proctor compaction effort for foamed bitumen treatment. The Optimum

Moisture Content found to be 8.75% with a Maximum Dry Density of 2.09 g/cc. The mixing

moisture content of proportioned material was decided based on optimum moisture content (i.e.

OMC=8.75%) and air dried field sample moisture content to prepare foamix.

Figure3. 9: samples of separated RAP and stone dust

1.98

2.00

2.02

2.04

2.06

2.08

2.10

2.0 3.5 5.0 6.5 8.0 9.5 11.0

Moisture content, %

Dry

dens

ity, g

/cc

Figure3. 10: OMC determination


3.6 OFC Determination for Emulsion Treatment The Optimum Fluid Content (OFC) was determined based on maximum Indirect Tensile Strength

(ITS) and maximum bulk density of Marshall Specimen prepared with 1.5% hydrated lime,

proportioned material (option1), 4% binder (6.02% Emulsion) and at varied percentages of water

content. The ITS and Bulk density of the Marshall Specimen were determined after a curing

period of 72 hours at 40 0C temperature and the testing was conducted at ambient temperature.

The graph (figure 3.11) was plotted keeping total fluid content on X-axis and Bulk density and

ITS on Y-axis to determine the OFC of the Emulsion treated material. From the graph Optimum

Fluid Content was decided (10.5+10.75)/2 = 10.625%.

Note: Total fluid content includes field moisture content, emulsion and additional water.

2.0352.0402.045

2.0502.0552.0602.0652.070

2.0752.0802.085

9.0 9.5 10.0 10.5 11.0 11.5 12.0

Total fluid content, %

Bul

k de

nsity

, g/c

c

140160180

200220240260280

300320340

ITS.

KPa

Bulk density

ITS

Figure3. 11: OFC determination


3.7 Recycled Cold Mix Preparation with Foamed Bitumen The graded material and different fillers (Cement, Hydrated lime and Fly-ash) in different percentages was

mixed using pug-mill type mixer since the quantity of mix was 10 kg. Initially dry mixing of proportioned

material was carried out for 10 to 15 seconds then additional water was added and then in to that mix

foamed bitumen was sprayed using WLB-10 fallowing the procedure described in Appendix A.2, after

setting the calculated and determined parameters (table 3.12) on the laboratory plant.

Figure3. 12: Mineral aggregates used in the study

Figure3. 13: WLB10 laboratory plant used to produce foamed bitumen


Figure3. 14: Pug-mill type mixer used to prepare foamix


Table 3.12: Material calculations for foamix preparation Air dried moisture content of proportioned mix (RAP+SD), MC air dry= 0.25 %

Bitumen flow rate = 125 g/s OMC=8.75 % PUG MILL mixer time factor=1.0 sample with 0 % filler (Mf=0) Percent foam bitumen (Pfb) 2 3 4 5 Bulk mass of sample, g (M) 10000 10000 10000 10000 Dry Mass of sample (Md) Md= M (1+MC air dry/100) 9975.06 9975.06 9975.06 9975.06 % Water to be added, (Pw) Pw=1+(0.5xOMC-MC airdry) 5.13 5.13 5.13 5.13 Mass of water, g (Mw) Mw=Pw x (Md+Mf)/100 511.22 511.22 511.22 511.22 Mass of bitumen, g (Mb) Mb=Pfb x( Md+Mf)/100 199.50 299.25 399.00 498.75 Time to be set on WLB 10, s (T) T=1.0 xMb/125 1.60 2.39 3.19 3.99 sample with 1 % filler (mass of filler, Mf = 100 g ) Percent foam bitumen (Pfb) 2 3 4 5 Bulk mass of sample, g (M) 10000 10000 10000 10000 Dry Mass of sample,g (Md) Md= M (1+MC air dry/100) 9975.06 9975.06 9975.06 9975.06 % Water to be added, (Pw) Pw=1+(0.5xOMC-MC airdry) 5.13 5.13 5.13 5.13 Mass of water, g (Mw) Mw=Pw x (Md+Mf)/100 516.35 516.35 516.35 516.35 Mass of bitumen, g (Mb) Mb=Pfb x( Md+Mf)/100 201.50 302.25 403.00 503.75 Time to be set on WLB 10, s (T) T=1.0 xMb/125 1.61 2.42 3.22 4.03 sample with 2 % filler (mass of filler, Mf = 200 g ) Percent foam bitumen (Pfb) 2 3 4 5 Bulk mass of sample, g (M) 10000 10000 10000 10000 Dry Mass of sample,g (Md) Md= M (1+MC air dry/100) 9975.06 9975.06 9975.06 9975.06 % Water to be added, (Pw) Pw=1+(0.5xOMC-MC airdry) 5.13 5.13 5.13 5.13 Mass of water, g (Mw) Mw=Pw x (Md+Mf)/100 521.47 521.47 521.47 521.47 Mass of bitumen, g (Mb) Mb=Pfb x( Md+Mf)/100 203.50 305.25 407.00 508.75 Time to be set on WLB 10, s (T) T=1.0 xMb/125 1.63 2.44 3.26 4.07 sample with 3 % filler (mass of filler, Mf = 300 g ) Percent foam bitumen (Pfb) 2 3 4 5 Bulk mass of sample, g (M) 10000 10000 10000 10000 Dry Mass of sample,g (Md) Md= M (1+MC air dry/100) 9975.06 9975.06 9975.06 9975.06 % Water to be added, (Pw) Pw=1+(0.5xOMC-MC airdry) 5.13 5.13 5.13 5.13 Mass of water, g (Mw) Mw=Pw x (Md+Mf)/100 526.60 526.60 526.60 526.60 Mass of bitumen, g (Mb) Mb=Pfb x( Md+Mf)/100 205.50 308.25 411.00 513.75 Time to be set on WLB 10, s (T) T=1.0 xMb/125 1.64 2.47 3.29 4.11


3.8 Recycled Cold Mix Preparation with Emulsion The graded material and different fillers (Cement, Hydrated lime and Fly-ash) in different

percentages that were used in foamix preparation, the same combination of materials used except

the binder bitumen emulsion instead of foamed bitumen. Hobart mixer was used to prepare the

mixture since the material quantity was 1150 grams only. Three different percentages of bitumen

emulsions were tried, after mixing in the mixer a delay of 30 minutes elapsed to simulate field

condition and to ensure starting of emulsion breaking process before starting compaction.

Marshall Specimen was cast with the mixture, the number of blows applied were 75 on each side.

Figure 3.15: Hobart mixer used to prepare emulsion mixture


3.9 Foamed bitumen and Bitumen Emulsion treated RAP Specimen testing The Marshall specimen prepared with formulated material have been tested for Bulk Density,

Resilient modulus (MR) and Indirect Tensile Strength (ITS) after a curing period of 24 hours at

room temperature in mold and 72 hours at 40 0C after taken out of mold. And testing was carried

out at room temperature only. Duplicate samples were tested for soaked Indirect Tensile Strength

after a soaking period of 24 hours in water bath at ambient temperature. Indirect Tension Test for

Resilient Modulus was carried out at a repetitive load 100 N, frequency 0.1 Hertz and at a

temperature of 25 0C. The test results of bulk density, indirect tensile strength and Indirect Tension

test for Resilient Modulus are presented in tables 3.13 and 3.14 with different binders.

Field cores cut from the Foamed bitumen treated recycled pavement layer were tested for Bulk

Density, Resilient modulus (MR), Indirect Tensile Strength (soaked and un-soaked) and dynamic

creep resistance. Some Laboratory cast specimens were also tested for dynamic creep resistance

since the uniaxial unconfined creep test is effective in identifying the sensitivity of asphalt

mixtures to permanent deformation or rutting. Dynamic creep test was conducted under

unconfined conditions at a temperature of 40 0C. The Specimens were placed in the temperature

control cabinet for a minimum period of two hours for conditioning the specimen to achieve test

temperature before testing. The contact stress of 3 kPa was applied for 0.1 second and rest period

of 0.9 second at a frequency of 1 Hz. The load was applied for a maximum of 3600 cycles. The

details specimens and dynamic creep test results are presented in table 3.15.

Figure3.16: Indirect Tensile Strength Testing Schematic diagram


Figure3.17: Specimen setup of Indirect Tension Test for Resilient Modulus

Figure3.18: Specimen setup of dynamic creep testing


Table 3.13 Foamed bitumen Specimen test results ITS, kPa

Mold ID

Filler type

Filler, %

Foamed Bitumen, %

Bulk Density,

g/cc

Average Bulk

Density, g/cc

Resilient Modulus,

MPa

Mean Resilient Modulus, MPa

Dry Soaked

TSR, %

0/2/1 2.107 1211 316.74

0/2/2 2

2.063 2.085

1425 1318

183.41 58

0/3/1 2.114 2090 353.89

0/3/2 3

2.182 2.148

800 1445

259.87 73

0/4/1 2.134 1845 372.66

0/4/2 4

2.132 2.133

1528 1687

322.41 87

0/5/1 2.129 2544 402.01

0/5/2

0%

5 2.131

2.130 1765

2155 318.31

79

1c/2/1 Cement 2.340 2519 329.83

1c/2/2 Cement 2

1.964 2.152

1517 2018

292.94 89

1c/3/1 Cement 2.188 2585 390.23

1c/3/2 Cement 3

2.127 2.158

2250 2417

405.37 104

1c/4/1 Cement 2.126 2132 437.23

1c/4/2 Cement 4

2.125 2.125

2362 2247

387.04 89

1c/5/1 Cement 2.148 2335 450.46

1c/5/2 Cement

1%

5 2.074

2.111 2464

2399 343.44

76

2c/2/1 Cement 2.144 2094 435.79

2c/2/2 Cement 2

2.140 2.142

2244 2169

305.23 70

2c/3/1 Cement 2.161 2188 448.34

2c/3/2 Cement 3

2.139 2.150

2201 2195

403.76 90

2c/4/1 Cement 2.152 2278 519.35

2c/4/2 Cement 4

2.155 2.153

2286 2282

376.00 72

2c/5/1 Cement 2.126 2300 359.33

2c/5/2 Cement

2%

5 2.077

2.101 2253

2277 301.16

84

3c/2/1 Cement 2.163 1957 484.19

3c/2/2 Cement 2

2.120 2.141

2028 1993

433.83 90

3c/3/1 Cement 2.117 2494 494.21

3c/3/2 Cement 3

2.121 2.119

1802 2148

426.57 86

3c/4/1 Cement 2.114 2058 512.92

3c/4/2 Cement 4

2.118 2.116

2287 2173

402.82 79

3c/5/1 Cement 2.110 2258 500.38

3c/5/2 Cement

3%

5 2.095

2.102 2390

2324 382.34

76

1L/2/1 Lime 2.105 1458 319.45

1L/2/2 Lime 2

2.064 2.084

2417 1938

246.99 77

1L/3/1 Lime 2.076 2410 324.26

1L/3/2 Lime 3

2.072 2.074

1986 2198

239.23 74

1L/4/1 Lime 2.073 2026 350.48

1L/4/2 Lime 4

2.068 2.071

2197 2112

299.39 85

1L/5/1 Lime 2.052 2178 271.54

1L/5/2 Lime

1%

5 2.004

2.028 1970

2074 257.83

95

2L/2/1 Lime 2.134 2162 289.15

2L/2/2 Lime 2

2.091 2.112

1446 1804

278.04 96

2L/3/1 Lime 2.078 1664 312.80

2L/3/2 Lime

2%

3 2.097

2.087 2326

1995 267.68

86


2L/4/1 Lime 2.083 2469 316.85

2L/4/2 Lime 4

2.047 2.065

1549 2009

306.38 97

2L/5/1 Lime 2.018 2617 294.92

2L/5/2 Lime 5

2.026 2.022

2189 2403

262.45 89

3L/2/1 Lime 2.134 2504 304.66

3L/2/2 Lime 2

2.126 2.130

1474 1989

245.29 81

3L/3/1 Lime 2.101 1902 344.37

3L/3/2 Lime 3

2.118 2.109

2081 1992

302.73 88

3L/4/1 Lime 2.091 2502 354.63

3L/4/2 Lime 4

2.070 2.080

2245 2374

321.17 91

3L/5/1 Lime 2.066 3026 374.33

3L/5/2 Lime

3%

5 2.060

2.063 1802

2414 345.65

92

1F/2/1 Fly-ash 2.070 1073 144.56

1F/2/2 Fly-ash 2

2.097 2.084

1233 1153

36.76 25

1F/3/1 Fly-ash 2.070 1271 187.75

1F/3/2 Fly-ash 3

2.073 2.071

1445 1358

49.46 26

1F/4/1 Fly-ash 2.034 1331 192.45

1F/4/2 Fly-ash 4

2.081 2.057

1464 1398

61.06 32

1F/5/1 Fly-ash 2.032 2312 182.64

1F/5/2 Fly-ash

1%

5 2.015

2.024 1222

1767

2F/2/1 Fly-ash 1286

2F/2/2 Fly-ash 2

2.126 2.126

1344 1315

2F/3/1 Fly-ash 2.126 1409 187.88

2F/3/2 Fly-ash 3

2.109 2.118

1931 1670

61.57 33

2F/4/1 Fly-ash 2.110 1556 208.35

2F/4/2 Fly-ash 4

2.092 2.101

2110 1833

68.53 33

2F/5/1 Fly-ash 2.080 2143 166.07

2F/5/2 Fly-ash

2%

5

2.080

2143

3F/2/1 Fly-ash 2.086 979 197.16

3F/2/2 Fly-ash 2

2.097 2.092

879 929

62.33 32

3F/3/1 Fly-ash 2.042 1034 203.38

3F/3/2 Fly-ash 3

2.151 2.097

1375 1205

70.58 35

3F/4/1 Fly-ash 2.090 1687 211.73

3F/4/2 Fly-ash 4

2.100 2.095

948 1318

101.97 48

3F/5/1 Fly-ash 2.070 1638 221.03

3F/5/2 Fly-ash

3%

5 2.031

2.051 1663

1651 91.74

42

Field cores 1 Cement 1.5% 3.5% 2.110 3350 525.8072

2 Cement 1.5% 3.5% 2.090 2374 403.3839

3 Cement 1.5% 3.5% 2.108 3416 342.1538

4 Cement 1.5% 3.5% 2.035

2.090

2302

2861

258.0461

155

Lab Cores 2c/3.5/1 Cement 1.5% 3.5% 2.118 3133 245

2c/3.5/2 Cement 1.5% 3.5% 2.168 1974 259

2c/3.5/3 Cement 1.5% 3.5% 2.089

2.125

1411

2173

252

96

2L/3.5/1 Lime 1.5% 3.5% 2.130 3149 201

2L/3.5/2 Lime 1.5% 3.5% 2.135 1508 218

2L/3.5/3 Lime 1.5% 3.5% 2.063

2.109

971

1876

285

90


2F/3.5/1 Fly-ash 1.5% 3.5% 2.075 1371 109

2F/3.5/2 Fly-ash 1.5% 3.5% 2.127 1605 166

2F/3.5/3 Fly-ash 1.5% 3.5% 2.124

2.109

1240

1405

154

68

Table 3.14 Bitumen Emulsion Specimen test results

ITS, kPa Specimen ID

Filler type Filler Emulsion

% Binder

%

Bulk Density,

g/cc

Average Bulk

Density, g/cc

Resilient Modulus,

MPa

Average Resilient Modulus,

MPa Dry Soaked

TSR, %

0/3/1 4.51 3 2.037 1089 241.72

0/3/2 4.51 3 2.017 2.028

851 970

130.15 54

0/4/1 6.02 4 2.043 718 278.91

0/4/2 6.02 4 2.039 2.041

1137 928

252.88 91

0/5/1 7.52 5 2.051 1089 241.72

0/5/2

0%

7.52 5 2.037 2.044

949 1019

223.13 92

1c/3/1 4.51 3 2.127 1184 200.81

1c/3/2 4.51 3 2.118 2.123

809 997

219.41 109

1c/4/1 6.02 4 2.087 973 219.41

1c/4/2 6.02 4 2.092 2.090

1048 1011

226.84 103

1c/5/1 7.52 5 2.080 1319 185.94

1c/5/2

1%

7.52 5 2.065 2.073

1471 1395

211.97 114

2c/3/1 4.51 3 2.117 1075 178.50

2c/3/2 4.51 3 2.105 2.111

1012 1044

215.69 121

2c/4/1 6.02 4 2.084 1376 167.34

2c/4/2 6.02 4 2.102 2.094

1017 1197

208.25 124

2c/5/1 7.52 5 2.091 1271 167.34

2c/5/2

2%

7.52 5 2.086 2.089

1416 1344

185.94 111

3c/3/1 4.51 3 2.107 1288 148.75

3c/3/2 4.51 3 2.115 2.111

1387 1338

159.91 108

3c/4/1 6.02 4 2.109 1238 197.09

3c/4/2 6.02 4 2.075 2.092

1513 1376

215.69 109

3c/5/1 7.52 5 2.068 1748 204.53

3c/5/2

CEM

ENT

3%

7.52 5 2.078 2.073

914 1331

215.69 105

1L/3/1 4.51 3 2.049 1448 167.34

1L/3/2 4.51 3 2.049 2.050

1355 1402

141.31 84

1L/4/1 6.02 4 2.060 1254 182.22

1L/4/2 6.02 4 2.058 2.059

1346 1300

178.50 98

1L/5/1 7.52 5 2.096 1816 238.00

1L/5/2

1%

7.52 5 2.087 2.092

1474 1645

193.37 81

2L/3/1 4.51 3 2.030 1475 185.94

2L/3/2 4.51 3 2.045 2.038

1062 1268

133.87 72

2L/4/1 6.02 4 2.054 1551 159.91

2L/4/2 6.02 4 2.042 2.049

2174 1862

145.03 91

2L/5/1 7.52 5 2.062 2270 152.47

2L/5/2

2%

7.52 5 2.071 2.067

2095 2183

133.87 88

3L/3/1 4.51 3 2.045 1017 163.62

3L/3/2 4.51 3 2.007 2.026

2451 1734

152.47 93

3L/4/1

LIM

E

3%

6.02 4 2.031 2.036 2270 2007 215.69 90


3L/4/2 6.02 4 2.040 1743 193.37

3L/5/1 7.52 5 2.047 3012 174.78

3L/5/2 7.52 5 2.072 2.060

2348 2680

159.91 91

2c/3.5/1 2.111 2360 226.84

2c/3.5/2 2.103 2.107268

2041 2201

264.03 116

2L/3.5/1 2.105 1409 211.97

2L/3.5/2 2.085 2.095507

1574 1492

226.84 107

2F/3.5/1 2.075 763.5 122.72

2F/3.5/2

2% 5.26 3.5

2.084 2.080262

952.5 858

156.19 127

Table3.15: Dynamic Creep Test results

S.NO Mold description

Creep

stiffness,

MPa

Total accumulated

axial strain at 1 hour

of loading, %

Remarks

1 1.5% Cement, 3.5% Foamed

bitumen 464.7 0.015 No failure

2 1.5% Lime, 3.5% Foamed bitumen 103.124 0.066 No failure

3 1.5% Fly-ash , 3.5% Foamed

bitumen 32.897

0.207 No failure

4 1.5% Cement, 5.26% Bitumen

Emulsion (3.5% Binder) 11.565 0.585

No failure

5 1.5% Lime, 5.26% Bitumen


Specimen failed at 1252nd cycle

6 1.5% Fly-ash, 5.26% Bitumen


Specimen failed at 1054th cycle

7 Field core of 1.5% cement, 3.5%

Foamed bitumen 30.5 0.222

No failure


3.10 Benkelman Beam Deflection testing Benkelman beam deflection study has been carried out on the pavement constructed with

Recycled mix of Foamed bitumen after three months of construction i.e. in the month of March

2006. The interval of deflection measurement points is selected as 30 meters and initial point is

marked at a distance of 10 meters from the zero Chainage of the Road (i.e. NH-17 Junction). The

pavement temperature observed was 37 0 C, The PI value and moisture content of subgrade soil

found to be 14% and 17% respectively. The temperature correction factor and moisture correction

factor applied are -0.02 and 1.1 respectively. The average characteristic rebound deflection of the

pavement found to be 1.17mm. This road can serve to a 2 million standard axles without provision

of any overlay.

Table3.16: Deflection data (LHS, towards Karnataka cold Storage Pvt. ltd) Chainage, km & m 00+010 00+040 00+070 00+100 00+130 00+160 00+190 00+220 00+250 00+280 00+310

Distance, m 10 40 70 100 130 160 190 220 250 280 310

Corrected Rebound

Deflection, mm 0.89 0.66 1.18 0.37 0.62 0.65 0.31 0.62 0.37 1.03 1.31

Table3.17: Deflection data (RHS, towards Karnataka cold Storage Pvt. ltd) Chainage, km & m 00+010 00+040 00+070 00+100 00+130 00+160 00+190 00+220 00+250 00+280 00+310

Distance, m 10 40 70 100 130 160 190 220 250 280 310

Corrected Rebound

Deflection, mm 1.2 0.99 1.01 1.16 0.33 0.62 1.06 1.32 1.23 1.14 0.57

BBD study

0.00

0.30

0.60

0.90

1.20

1.50

0 30 60 90 120 150 180 210 240 270 300 330Distance, m

Reb

ound

Def

lect

ion,

m

m

RHS

LHS

Figure3.19: Benkelman Beam rebound deflection variation with distance


_________________________________________CHAPTER - 4

4. RESULTS AND ANALYSIS

4.1 Results of Foamed Bitumen Treated RAP Marshall Specimens

Bulk density:

The graphs are plotted to see the variation in bulk density with active filler and foamed bitumen.

The bulk density of the Marshall specimens was increased and then decreased as the foamed

bitumen content increases when there was no active filler. As the cement content increases there

was no significant increase in bulk density where as the binder increase causes a decrease in bulk

density. Maximum bulk density observed from graph 4.1a, was 2.16 g/cc at 3% foamed bitumen

and 1.1% cement.

When lime used as filler, increased bulk density was observed at increased lime content where as

increase in foamed bitumen decreased the bulk density. Maximum bulk density observed from

graph 4.1b, was 2.145 g/cc at 0% filler and 3% foamed bitumen and 2.13 g/cc at 3% lime and 2%

foamed bitumen.

Addition of fly-ash to the mix caused decrease in bulk density.

Table4.1: Maximum bulk density values from the Graphs 4.1(a, b, c)

Foamed bitumen, % Cement content, % Maximum bulk density, g/cc2 1.25 2.155 3 1.1 2.160 4 2 2.155 5 0 2.130

Foamed bitumen, % Lime content, % Maximum bulk density, g/cc2 3 2.130 3 0 2.145 4 0 2.120 5 0 2.130

Foamed bitumen, % Fly-ash content, % Maximum bulk density, g/cc2 1.75 2.125 3 0 2.150 4 0 2.120 5 0 2.130


Variation of Bulk density with Cement

2.0002.020

2.0402.0602.0802.100

2.1202.1402.1602.180

2.2002.220

0% 1% 2% 3% 4%Cement content, %

Bulk

den

sity

, g/c

c

2% Binder

3% Binder

4% Binder

5% Binder

Variation of Bulk density with Lime

2.0002.0202.0402.0602.0802.100

2.1202.1402.1602.1802.2002.220

0% 1% 2% 3% 4%Lime content, %

Bul

k de

nsity

, g/c

c

2% Binder

3% Binder

4% Binder

5% Binder

Variation of Bulk density with Fly ash

2.0002.0202.040

2.0602.0802.1002.1202.1402.160

2.1802.2002.220

0% 1% 2% 3% 4%Fly ash content, %

Bul

k de

nsity

, g/c

c

2% Binder

3% Binder4% Binder

5% Binder

Graph4. 2:( a, b, c) Variation of bulk density with foamed bitumen and filler


Resilient modulus (MR):

The values of Resilient modulus were plotted in graphs and then linear trend lines were drawn to

observe the variation in MR with foamed bitumen and active filler. It was observed from the

graphs 4.2 a, b that the increase in foamed bitumen and increase in cement increased the MR but at

higher cement contents and at higher foamed bitumen contents increase in MR was not much

significant. The optimum cement content ranges from 1 to 2% and optimum foamed bitumen

content ranges from 3 to 4%. The maximum MR values observed from the graphs 4.2a and b was

2372 MPa at 1% cement and 5% foamed bitumen and 2350 MPa at 3% cement and 3% foamed

bitumen. Similar trend was observed when the active filler used was lime with a difference of

significant increase in MR at higher contents of lime and foamed bitumen. The maximum MR

values observed from the graphs 4.3a and b was 2400 MPa at 3% lime and 5% foamed bitumen

and 2375 MPa at 3% lime and 4% foamed bitumen. When fly-ash used as filler the variation

observed was not much but at higher foamed bitumen contents there was an increase in MR. the

Maximum MR value observed from the graph 4.4 a and b was 2125 MPa at 2% fly ash and 5%

foamed bitumen.


Table 4.2: Maximum Resilient modulus (MR) values from the Graphs 4.2(a, b) Cement content, % Foamed bitumen, % Maximum Resilient modulus, MPa

0 5 2100 1 5 2372 2 5 2270 3 5 2250

Foamed bitumen, % Cement content, % Maximum Resilient modulus, MPa

2 3 2150 3 3 2350 4 3 2350 5 3 2350

Variation of MR with Foamed Bitumen and Cement

500750

10001250150017502000225025002750300032503500

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5Foamed bitumen, %

Res

ilien

t mod

ulus

, MPa

0% Filler

1% Cement

2% Cement

3% Cement

Variation of MR with Cement

500

1000

1500

2000

2500

3000

3500


Res

ilien

t mod

ulus

, MPa

2% Foam bitumen

3% Foam bitumen

4% Foam bitumen

5% Foam bitumen

Graph4.2 :( a, b) Variation of Resilient Modulus with foamed bitumen and Cement


Table4.3: Maximum Resilient modulus (MR) values from the Graphs 4.3 (a, b) Lime content, % Foamed bitumen, % Maximum Resilient modulus, MPa

0 5 2100 1 5 2150 2 5 2300 3 5 2400

Foamed bitumen, % Lime content, % Maximum Resilient modulus, MPa

2 3 2000 3 3 2125 4 3 2375 5 3 2400

Variation of MR with Foamed bitumen and Lime

500750

10001250150017502000225025002750300032503500

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5Foamed bitumen, %

Res

ilien

t mod

ulus

, MPa

0% Filler

1% Lime

2% Lime

3% Lime

Variation of MR with Lime

500

1000

1500

2000

2500

3000

3500

0% 1% 2% 3% 4%Lime content, %

Res

ilien

t mod

ulus

, MPa

2% Foamed betumen

3% Foamed bitumen

4% Foamed bitumen

5% Foamed bitumen

Graph4.3 :( a, b) Variation of Resilient Modulus with foamed bitumen and Lime


Table4.4: Maximum Resilient modulus (MR) values from the Graphs 5.6(a, b) Fly-ash content, % Foamed bitumen, % Maximum Resilient modulus, MPa

0 5 2100 1 5 1700 2 5 2125 3 5 1650

Foamed bitumen, % Fly-ash content, % Maximum Resilient modulus, MPa

2 0 1350 3 0 1500 4 0 1700 5 0 2100

Variation of MR with Foamed bitumen and fly-ash

500750

10001250150017502000225025002750300032503500

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5Foamed bitumen, %

Res

ilien

t mod

ulus

, MPa

0% Filler

1% Flyash

2% Flyash

3% Flyash

Variation of MR with Flyash

500

1000

1500

2000

2500

3000

3500

0% 1% 2% 3% 4%Flyash content, %

Res

ilien

t mod

ulus

, MPa

2% Foamed bitumen

3% Foamed bitumen

4% Foamed bitumen

5% Foamed bitumen

Graph4.4 :( a, b) Variation of Resilient Modulus with foamed bitumen and Fly-ash


Indirect tensile strength (ITS):

The ITS values were increased and then decreased with increase in foamed bitumen. The addition

of cement increased the ITS values significantly. The maximum ITS observed was 510 kPa at 3%

cement and 4% foamed bitumen. When the crusher stone dust was replaced with lime it was

observed that the decrease in ITS initially and then at higher lime content slight increase. The

maximum ITS observed was 375 kPa at 3% lime and 5% foamed bitumen. Addition of fly ash

caused to decrease the ITS drastically. The specimens with cement and lime were observed to be

very less susceptible to moisture as it was observed from soaked ITS of the specimen.

Table 4.5: Maximum Dry Indirect Tensile Strength (ITS) values from the Graphs 4.5 (a, b, c)

Cement content, % Foamed bitumen, % Maximum Dry Indirect Tensile Strength, kPa0 5.00 400 1 5.00 450 2 3.25 490 3 4.00 510

Lime content, % Foamed bitumen, % 1 3.25 350 2 3.50 325 3 5.00 375

Fly-ash content, % Foamed bitumen, % 1 4.00 200 2 3.75 210 3 5.00 225

Table 4.6: Maximum soaked Indirect Tensile Strength (ITS) values

Cement content, % Foamed bitumen, % Maximum Soaked Indirect Tensile Strength, kPa0 4.50 325 1 3.75 400 2 3.50 400 3 2.00 430

Lime content, % Foamed bitumen, % 1 4.0 275 2 3.5 290 3 5.0 340

Fly-ash content, % Foamed bitumen, % 1 5 75 2 5 75 3 5 100


Variation of Dry ITS with Foamed bitumen and cement

050

100

150200250300350400

450500550

1.5 2 2.5 3 3.5 4 4.5 5 5.5Foamed bitumen, %

Dry

ITS,

KPa

0% Filler

1% Cement

2% Cement

3% Cement

Variation of Dry ITS with Foamed bitumen and lime

050

100150

200250

300350

400450

500550

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5Foamed bitumen, %

Dry

ITS,

KPa

0% Filler

1% Lime

2% Lime

3% Lime

Variation of Dry ITS with Foamed bitumen and fly-ash

050

100150200250300350400450500550

1.5 2 2.5 3 3.5 4 4.5 5 5.5

Foamed bitumen, %

Dry

ITS,

KPa

0% Filler

1% Flyash

2% Flyash

3% Flyash

Graph4.5: (a, b, c) Variation of dry ITS with foamed bitumen


4.2 Results of Emulsified Bitumen Treated RAP Marshall Specimens Bulk density:

The graphs are plotted to see the variation in bulk density with active filler and emulsified

bitumen. The bulk density of the Marshall specimens was decreased with increase in emulsion

binder content. Addition of cement increased the bulk density but as the cement content increases

there was no significant change in bulk density. Maximum bulk density observed was 2.12 g/cc at

3% binder and 1% cement.

When lime used as filler increased bulk density was observed to increase initially but as the lime

content increased it was decreased. Maximum bulk density observed from graph 4.6(a, b), was

2.14 g/cc at 3% lime and 2% emulsion binder.

Table4. 16: Maximum bulk density values From the Graphs 4.6 (a, b) Cement content, % Emulsion binder, % Maximum bulk density, g/cc

0 5 2.045 1 3 2.120 2 3 2.110 3 3 2.110

Lime content, % Emulsion binder, % Maximum bulk density, g/cc1 5 2.095 2 5 2.065 3 2 2.14

Variation of Bulk Density w ith Cement and emulsion

1.9802.0002.0202.0402.0602.0802.1002.1202.1402.1602.1802.200


Bul

k D

ensi

ty, g

/cc

3% Binder

4% Binder

5% Binder

Variation of Bulk Density w ith Lime and emulsion

1.9802.0002.0202.0402.0602.0802.1002.1202.1402.1602.1802.200

0% 1% 2% 3% 4%

Lime content, %

Bul

k D

ensi

ty, g

/cc

3% Binder

4% Binder

5% Binder

Graph4.6 :( a ,b) Variation of bulk density with Bitumen Emulsion


Resilient modulus (MR): The values of Resilient modulus were plotted in graphs and then linear trend lines were drawn to

observe the variation in MR with emulsion and active filler. It was observed from the graphs 4.7 a,

b that MR was increased with both binder content and active fillers (lime and cement). The

increase in MR was not much significant with cement but with lime at 5% binder, increase in MR

was significant. In comparison with cement lime showed much better MR values at same binder

contents. The maximum MR values observed from the graphs 4.7a and b was 2650 MPa at 3%

lime and 5% emulsified binder and 1400 MPa at 3% cement and 3% emulsified binder.

Table4. 17: Maximum Resilient Modulus values from the Graphs 4.7 (a, b) Cement content, % Emulsion binder, % Maximum Resilient Modulus, MPa

0 5 1000 1 5 1350 2 5 1400 3 3,4,5 1400

Lime content, % 0 5 1000 1 5 1600 2 5 2250 3 5 2650

Variation of MR with Cement and emulsion

0

200

400

600

800

1000

1200

1400

1600


Res

ilien

t mod

ulus

, MPa

3% Binder

4% Binder

5% Binder

Variation of MR with Lime and emulsion

0

500

1000

1500

2000

2500

3000

0% 1% 2% 3% 4%Lime content

Res

ilien

t mod

ulus

, MPa

3% Binder

4% Binder

5% Binder

Graph4.7 :( a, b) Variation of Resilient Modulus with Bitumen Emulsion


Indirect tensile strength (ITS):

The ITS values were increased and then decreased with increase in emulsion. The addition of

cement decreased the ITS. The maximum dry and soaked ITS observed was 275 kPa at 0% cement

and 4% binder and 250 kPa at 0% cement and 4% binder respectively. Addition of lime caused to

decrease the ITS. The specimens with cement and lime were observed to be very less susceptible

to moisture as it was observed from soaked ITS of the specimen. It was observed that soaked ITS

of cement treated material was slightly more than the dry ITS.

Table 4. 18: Maximum Dry and Soaked Indirect Tensile Strength (ITS) values from the Graphs 4.8 (a, b) and 4.9 (a, b).

Cement content, % Emulsion binder, % Maximum Dry Indirect Tensile Strength, KPa 0 4 275 1 4 220 2 3 175 3 4.5 200

Cement content, % Emulsion binder, % Maximum Soaked Indirect Tensile Strength, KPa0 4 250 1 4 225 2 3 220 3 4 220

Lime content, % Emulsion binder, % Maximum Dry Indirect Tensile Strength, kPa 1 5 240 2 3 180 3 4 220

Lime content, % Emulsion binder, % Maximum Soaked Indirect Tensile Strength, kPa 1 5 190 2 4 150 3 4 200


Variation of Dry ITS with emulsion and cement

0

50

100150

200

250

300

350

400450

500

550

2.5 3.0 3.5 4.0 4.5 5.0 5.5Binder content, %

ITS,

KPa

0% Filler

1% Cement

2% Cement

3% Cement

Variation of Soaked ITS w ith emulsion and cement

50

100

150

200

250

300

350

400

450

500

550

2.5 3.0 3.5 4.0 4.5 5.0 5.5Binder content, %

ITS,

KPa

0% filler

1% cement

2% Cement

3% cement

Graph4.8: (a, b) Variation of ITS with Bitumen Emulsion and Cement

Variation of Dry ITS w ith emulsion and lime

050

100150200250300350400450500550

2.5 3.0 3.5 4.0 4.5 5.0 5.5Binder content, %

ITS,

KPa

0% Filler

1% Lime

2% Lime

3% Lime

Variation of Soaked ITS w ith emulsion and lime

050

100150200250

300350400450500550

2.5 3.0 3.5 4.0 4.5 5.0 5.5Binder content, %

ITS,

KPa

0% filler

1% Lime

2% Lime

3% Lime

Graph4.9 :( a, b) Variation of ITS with Bitumen Emulsion and lime


4.3 Field and Laboratory Core Comparison Comparison of Field cores and Lab cores were made with same binder i.e. foamed bitumen 3.5%

and different fillers of 1.5% (Viz. Cement, Lime and Fly-ash). The MR and ITS of field cores

were higher than the laboratory cast cores but the bulk density of the field cores were less when

compared with laboratory cast cores. MR and ITS of Laboratory Cores with fly-ash were poor

when compared with filler as lime or cement.

Resilient Modulus variation in different cores

2861

21731876

1405

0

500

1000

1500

2000

2500

3000

3500R

esili

ent m

odul

us, M

Pa

Field core Lab core with CementLab core with Lime Lab core with Flyash

Dry ITS Variation in different cores

300

256 243

160

0

50

100

150

200

250

300

350

ITS

, kPa

Field core Lab core with cementLab core with Lime Lab core with Flyash

Variation of bulk density in different cores

2.0902.125 2.109 2.109

2.0002.0202.0402.0602.0802.1002.1202.1402.1602.1802.2002.220

Bulk

den

sity

, g/c

c

Field core lab core with Cement

lab core with Lime lab core with Flyash Graph4.10 :( a, b, c) Variation of Resilient Modulus, Bulk density and ITS in different cores


4.4 Dynamic Creep Test Results Analysis Laboratory cores prepared with foamed bitumen and cement were very strong against dynamic

axial loading in comparison with any other cores, even field cores. Field cores have shown very

poor resistance in comparison with laboratory cores. Accumulated axial strain was nominal in case

of foamed bitumen treated cores in comparison with emulsion treated cores. The cores treated with

emulsion & lime and emulsion & fly ash have failed before completion of total number of loading

cycles. Laboratory cores with emulsion and cement have shown better resistance in comparison

with other emulsion treated cores.

At 3.5%Foamed bitumen and 1.5% filler

0

0.05

0.1

0.15

0.2

0.25

0 1000 2000 3000 4000

Number of cycles

Acu

mul

ated

axi

al s

trai

n, %

cement

lime

fly-ash

field core

At 5.25% Emulsion(3.5% Binder) and 1.5% filler

0

0.5

1

1.5

2

2.5

3

3.5

0 1000 2000 3000 4000Number of cycles

Acc

umul

ated

axi

al s

trai

n, %

cement

lime

fly-ash

Graph4.11 :( a, b, c) Variation of Accumulated axial strain with Number of cycles


At 3.5% binder and 1.5% cement

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1000 2000 3000 4000

Number of cycles

Acc

umul

ated

axi

al s

trai

n, %

foamed botumen

Emulsion

At 3.5% binder and 1.5% Lime

0

0.5

1

1.5

2

2.5

3

0 1000 2000 3000 4000

Number of cycles

Acc

ulm

ulat

ed a

xial

str

ain,

% Emulsion

Foamed bitumen

At 3.5% binder and 1.5% flyash

0

0.5

1

1.5

2

2.5

3

3.5

0 1000 2000 3000 4000Number of cycles

Acc

umul

ated

sxi

al s

trai

n, %

Emulsion

Foamed bitumen

Graph4.12 :( a, b) Variation of Accumulated axial strain with Number of cycles


________________________________________CHAPTER – 5

5. CONCLUSIONS The following conclusions are drawn based on the studies performed on emulsion treated and

foamed bitumen treated RAP in laboratory and Field.

In comparison with bitumen emulsion, foamed bitumen treated RAP has shown better

bulk density, indirect tensile strength, resilient modulus and dynamic creep stiffness

with same aggregate and gradation

Loss of strength on soaking is very less with foamed bitumen and lime/cement treated

material, in most of the cases the tensile strength ratio ranges from 70 to 100% and it

is 155% in case of field cores

Emulsion treated RAP with cement has shown higher soaked ITS than dry ITS

In view of bulk density, indirect tensile strength, resilient modulus and dynamic creep

stiffness, out of three fillers used in the present study cement has shown best results in

combination with foamed bitumen and the optimum cement content ranges from 1 to

2% by weight aggregates. At higher cement contents improvement in properties are not

much significant

Lime has shown almost similar densities, ITS and MR values to compare with cement

treated materials at higher lime contents

Fly-ash in combination with foamed bitumen of 5% has shown a minimum MR of

1500 MPa and minimum dry ITS of 200 kPa. In combination with cement and foamed

bitumen the fly-ash could be a use full material to treat the existing materials

Loss of ITS on soaking in fly-ash and foamed bitumen treated RAP was considerable

i.e. tensile strength ration ranges from 25 to 50%

Cores cut from the foamed bitumen treated pavement have shown higher ITS and MR

values in comparison with laboratory cast cores

Dynamic creep stiffness of Cores from the field was very less in comparison with

laboratory cast cores but they were comparable to HMA cores

Benkelman beam deflection study on foamed bitumen treated pavement shows that it

was structurally sound with an average characteristic rebound deflection of 1.17mm

and no functional failure was observed


________________________________________CHAPTER – 6

6. APPENDICES

Appendix 1: Material Sampling and blending 1.1 Field sampling

Bulk samples are obtained during field investigations and test pit excavations. Each layer in the

upper pavement (± 300 mm) must be sampled separately and at least 150 kg of material is

recovered from each layer that is likely to be included in any mix design procedure.

1.2 Preparation of samples for mix design procedure

1.2.1 Standard soil tests

Determine the grading (ASTM D 422) and plasticity index (ASTM D 4318) of the material

sampled from each individual layer.

1.2.2 Sample blending

Where necessary, blend the materials sampled from the different layers to obtain a combined

sample representing the material from the full recycling depth. The in-situ density of the various

components must be considered when blending materials, as illustrated in the boxed example

below. Repeat the tests described in 1.2.1 above to determine the grading and plasticity index of

the blended sample.

1.2.3 Representative proportioning

Separate the material in the representative sample into the following four fractions:

i. Retained on the 19.0 mm sieve;

ii. Passing the 19.0 mm sieve, but retained the 13.2 mm sieve;

iii. Passing the 13.2 mm sieve, but retained on the 4.75 mm sieve; and

iv. Passing the 4.75 mm sieve.


Reconstitute representative samples in accordance with the grading up to the portion passing the

19.0 mm sieve. Substitute the portion retained on 19.0 mm sieve with material that passes the 19.0

mm sieve, but is retained on the 13.2 mm sieve. The example in the table below explains this

procedure:

If there is insufficient material (i.e. passing the 19.0 mm sieve but retained on the 13.2 mm sieve)

for substituting that retained on the 19 mm sieve, then lightly crush the material retained on the

19.0 mm sieve to provide more of this fraction.

1.2.4 Sample quantities

The guidelines shown in Table 7.1 should be used for the quantity of material required for the

respective tests:

Table 7.1

Test Sample quantity required

Modified proctor, AASHTO T180 5 x 7 kg

Indirect Tensile Strength (150mm Dia) 20 kg per stabiliser content

Unconfined Compressive Strength (150mm Dia) 20 kg per stabiliser content

Bituminous Stabilization Design (Marshall briquettes) Minimum 10 kg per stabiliser content

Moisture contents Approximately 1kg

1.2.5 Hygroscopic moisture content

Two representative air-dried samples, each approximately 1 kg, are used to determine the

hygroscopic (air dried) moisture content of the material. (Note: Larger sample size should be used

for more coarsely graded materials.) Weigh the air-dried samples, accurate to the nearest 0.1 g,

and then place them in an oven at a temperature of between 105 ºC and 110 ºC until they achieve

constant mass. The hygroscopic moisture content is the loss of mass expressed as a percentage of

the dry mass of the sample.


Appendix 2: Mix Design Procedure for Bitumen Stabilised Materials

2.1 Active filler requirements Bitumen stabilisation is normally carried out in combination with a small amount of active filler

(cement or hydrated lime). The following application rates (by mass) of hydrated lime or cement

should be used as a guide:

Plasticity Index < 10 Plasticity Index: 10 - 16 Plasticity Index: >16

Add 1% Cement Add 1% Lime Pre-treat with 2% Lime

Pretreatment requires that the lime and water be added at least 4 hours prior to the addition of the

bitumen emulsion or foamed bitumen. The treated material must be placed in an air-tight container

to retain moisture. However, due to the hydration process, the moisture content should always be

checked and, if necessary, adjusted prior to adding the bitumen stabilising agent.

Although the use of active fillers is recommended, in parts of the world, these agents are not

readily available. In such cases, the use of crusher dust (minus 6 mm crusher tailings) or similar

material can be used. Additional tests without active filler and/or with crusher dust are carried out

during the mix design process. The results of these tests allow a decision to be made as the

whether the addition of an active filler or crusher dust is warranted.


2. 2 Determination of Optimum Fluid Content (OFC) and Maximum Dry

Density (MDD) for the treated material

Note: For foamed bitumen stabilisation, the OFC and MDD can be assumed to be the same as the

OMC and MDD determined for representative samples of the untreated material.

The OFC for bitumen emulsion treated material is the percentage by mass of bitumen emulsion

plus additional moisture required to achieve the maximum dry density in the treated material. As

described below, the OFC is determined by adding a constant percentage of bitumen emulsion

whilst varying the amount of water added.

STEP 1

Measure out the bitumen emulsion as a percentage by mass of the air-dried material for each of

five prepared samples. The percentage of bitumen emulsion added is normally between 2 and 3%

residual bitumen (e.g. for 3% residual bitumen, add 5% of a 60 % bitumen emulsion).

STEP 2

The bitumen emulsion and water is added to the material and mixed until uniform immediately

prior to compacting the specimens.

STEP 3

Determine the OFC and MDD for the stabilised material in accordance with the modified

moisture-density relationship test procedure (AASHTO T-180).


2. 3 Preparation of bitumen stabilised material

2. 3.1 Preparation of materials for bitumen emulsion stabilization

STEP 1

Place the required quantity of sample into a suitable mixing container (10 kg for the manufacture

of 100 mm diameter briquettes, or 20 kg for the manufacture of 150 mm diameter briquettes).

STEP 2

Determine the dry mass of the sample using equation

Msample = Mair-dry / (1 + (Wair-dry / 100))

Where: Msample = dry mass of the sample [g]

Mair-dry = air-dried mass of the sample [g]

Wair-dry = moisture content of air-dried sample [% by mass]

STEP 3

Determine the required percentage of active filler (lime or cement) using equation

Mcement = (Cadd / 100) x Msample

Where: Mcement = mass of lime or cement to be added [g]

Cadd = percentage of lime or cement required [% by mass]

Msample = dry mass of the sample [g]

STEP 4

Determine the required percentage (by mass) of bitumen emulsion using equation

Memul = (RBreqd / PBE) x Msample

Where: Memul = mass of bitumen emulsion to be added [g]

RBreqd = percentage of residual bitumen required [% by mass]

PBE = percentage of bitumen in emulsion [% by mass]


STEP 5

Determine the amount of water to be added for optimum compaction purposes using equation

Mwater = {((WOFC – Wair-dry) / 100) x Msample} – Memul

Where: WOFC = optimum fluid content [% by mass]


Mwater = mass of water to be added [g]


Memul = mass of bitumen emulsion to be added [g]


STEP 6

Mix the material, active filler, bitumen emulsion and water together until uniform. Immediately

manufacture briquette specimens following the relevant procedure for either 100 mm or 150 mm

diameter briquettes.

STEP 7

Samples are taken during the compaction process to determine the moulding moisture content.

2.3.2 Preparation of materials for foamed bitumen stabilization

2.3.2.1 Determination of the foaming properties of the bitumen

The foaming properties of each bitumen type are characterized by:

– Expansion Ratio. A measure of the viscosity of the foamed bitumen, calculated as the ratio of

the maximum volume of the foam relative to the original volume of bitumen; and

– Half-life. A measure of the stability of the foamed bitumen, calculated as the time taken in

seconds for the foam to collapse to half of its maximum volume.

The objective is to determine the temperature and percentage of water addition that is required to

produce the best foam properties (maximum expansion ratio and half-life) for a particular source

of bitumen. This is achieved at three different bitumen temperatures as follows:

STEP 1

Heat the bitumen in the kettle of the Wirtgen WLB 10 laboratory unit with the pump circulating

the bitumen through the system until the required temperature is achieved (normally starting with

160 °C). Maintain the required temperature for at least 5 minutes prior to commencing with

testing.

STEP 2

Calibrate the discharge rate of the bitumen and set the timer on the Wirtgen WLB 10 to discharge

500 g of bitumen.

STEP 3

Set the water flow-meter to achieve the required water injection rate (normally starting with 2% by

mass of the bitumen).

STEP 4


Discharge foamed bitumen into a preheated (± 75 °C) steel drum for a calculated spray time for

500 g of bitumen. Immediately after the foam discharge stops, start a stopwatch.

STEP 5

Using the dipstick supplied with the Wirtgen WLB 10 (which is calibrated for a steel drum of 275

mm in diameter and 500 g of bitumen) measure the maximum height the foamed bitumen achieves

in the drum. This is recorded as the maximum volume.

STEP 6

Use the stopwatch to measure the time in seconds that the foam takes to dissipate to half of its

maximum volume. This is recorded as the foamed bitumen’s half-life.

STEP 7

Repeat the above procedure three times or until similar readings are achieved.

STEP 8

Repeat steps 3 to 7 for a range of at least three water injection rates. Typically, values of 2%, 3%

and 4% by mass of bitumen are used.

STEP 9

Plot a graph of the expansion ratio versus half-life at the different water injection rates on the same

set of axes (see the example in Figure 7.1). The optimum water addition is chosen as an average of

the two water contents required to meet these minimum criteria.

Repeat Step 1 to 9 for two other bitumen temperatures (normally 170 °C and 180 °C).


Figure 7.1 Determination of optimum foaming water content

The temperature and optimum water addition that produces the best foam is then used in the mix

design procedure described below.

Note: The minimum foaming properties that are acceptable for effective stabilisation are:

Expansion ratio: 8 times

Half-life: 6 seconds

If these minimum requirements cannot be met, the bitumen should be rejected as unsuitable for

foaming.

2. 3.2.2 Sample preparation for foamed bitumen treatment

STEP1

Place the required quantity of sample into a suitable mixing container (10 kg for the manufacture

of 100 mm diameter briquettes, or 20 kg for the manufacture of 150 mm diameter briquettes).

STEP2

Determine the dry mass of the sample using equation

Msample = Mair-dry / (1 + (Wair-dry / 100))


Where: Msample = dry mass of the sample [g]

Mair-dry = air-dried mass of the sample [g]


STEP3

Determine the required percentage of active filler (lime or cement) using equation

Mcement = (Cadd / 100) x Msample

Where: Mcement = mass of lime or cement to be added [g]

Cadd = percentage of lime or cement required [% by mass]


STEP4

Determine the percentage of water to be added for optimum mixing moisture content as calculated

using equation A. The amount of water to be added to the sample is determined using equation B.

Wadd = 1 + (0.5 WOMC – Wair-dry) ---------------- [Equation A]

Mwater = (Wadd / 100) x (Msample + Mcement) ------- [Equation B]

Where: Wadd = water to be added to sample [% by mass]

WOMC = optimum moisture content [% by mass]

Wair-dry = water in air-dried sample [% by mass]

Mwater = mass of water to be added [g]


Mcement = mass of lime or cement to be added [g]

STEP 5

Mix the material, active filler and water in the mixing bowl until uniform.

Note: Inspect the sample after mixing to ensure that the mixed material is not packed against the

sides of the mixer. If this situation occurs, mix a new sample at a lower moisture content. Check to

see that the material mixes easily and remains in a “fluffy” state. If any dust is observed at the end

of the mixing process, add small amounts of water and remix until a “fluffy” state is achieved with

no dust.

STEP 6

Determine the foamed bitumen to be added using equation:

Mbitumen = (Badd / 100) x (Msample + Mcement) Where: Mbitumen= mass of foamed bitumen to be added [g]


Badd = foamed bitumen content [% by mass]



STEP 7

Determine the timer setting on the Wirtgen WLB 10 using equation:

T = factor x (Mbitumen + Qbitumen) Where: T = time to be set on WLB 10 timer [s]

Mbitumen= mass of foamed bitumen to be added [g]

Qbitumen= bitumen flow rate for the WLB 10 [g/s]

factor = compensation for bitumen losses on the mixing equipment.

Experience has shown that a factor of 1.1 is applicable where a Hobart mixer is used and 1.0 when

using a pug mill-type mixer.

STEP 8

Position the mechanical mixer adjacent to the foaming unit so that the foamed bitumen can be

discharged directly into the mixing bowl.

STEP 9

Start the mixer and allow it to mix for at least 10 seconds before discharging the required mass of

foamed bitumen into the mixing bowl. Continue mixing for a further 30 seconds after the foamed

bitumen has discharged into the mixer.

STEP 10

Determine the amount of water required to bring the sample to the optimum moisture content

using equation.

Mplus = (WOMC – Wsample) / 100 x (Msample + Mcement) Where: Mplus = mass of water to be added [g]

WOMC = optimum moisture content [% by mass]

Wsample = moisture content of prepared sample [% by mass]



STEP 11

Add the additional water and mix until uniform.

STEP 12


Transfer the foamed bitumen treated material into a container and immediately seal the container

to retain moisture. To minimize moisture loss from the prepared sample, manufacture briquette

specimens as soon as possible following the relevant procedure for either 100 mm or 150 mm

diameter briquettes.

Repeat the above steps for at least four different foamed bitumen contents.

2.3.4 Manufacture of 100 mm diameter briquette specimens

2.3.4.1 Compaction (Marshall Method)

STEP 1

Prepare the Marshall mould and hammer by cleaning the mould, collar, base-plate and face of the

compaction hammer. Note: the compaction equipment must not be heated but kept at ambient

temperature.

STEP 2

Weigh sufficient material to achieve a compacted height of 63.5 mm ± 1.5 mm (usually 1150 g is

adequate). Poke the mixture with a spatula 15 times around the perimeter and 10 times on the

surface, leaving the surface slightly rounded.

STEP 3

Compact the mixture by applying 75 blows with the compaction hammer. Care must be taken to

ensure the continuous free fall of the hammer.

STEP 4

Remove the mould and collar from the pedestal, invert the briquette (turn over). Replace it and

press down firmly to ensure that it is secure on the base plate. Compact the other face of the

briquette with a further 75 blows.

STEP 5

After compaction, remove the mould from the base-plate and extrude the briquette by means of an

extrusion jack.

Note: With certain materials lacking cohesion, it may be necessary to leave the specimen in the

mould for 24 hours, allowing sufficient strength to develop before extracting.

2.3.4.2 Curing procedure

Place the briquettes on a smooth flat tray and cure in a forced-draft oven for 72 hours at 40 °C. Remove

from oven after 72 hours and allow cooling to ambient temperature.

.2.3.5 Determination of optimum bitumen content for bitumen stabilised materials


The 100 mm diameter briquettes are tested for indirect tensile strength under dry and soaked conditions.

The results of the dry and soaked ITS tests are plotted against the respective bitumen content that

was added. The added bitumen content that best meets the desired properties is regarded as the

optimum bitumen content.

2.3.6. Compaction (modified AASHTO T-180 method)

STEP 1

Prepare and treat 24 kg of sample at the optimum bitumen content.

STEP 2

Where required, add sufficient moisture to bring sample to optimum compaction moisture content

and mix until uniform. Immediately after mixing, place material in an airtight container.

STEP 3

Take ±1 kg representative samples after compaction of the first and third briquette and dry to a

constant mass. Determine the moulding moisture using equation

Wmould = (Mmoist – Mdry) / Mdry x 100

Where: Wmould = moulding moisture content [% by mass]

Mmoist = mass of moist material [g]

Mdry = mass of dry material [g]

STEP 4

Compact at least 4 briquettes using a 150 mm diameter split-mould, applying modified AASHTO

(T-180) compaction effort (5 layers approximately 25 mm thick, 55 blows per layer using a 4.536

kg hammer with a 457 mm drop).

STEP 5

Carefully trim excess material from briquettes, as specified in the AASHTO T-180 test method.

STEP 6

Carefully remove briquette from the spilt-mould and place on a smooth flat tray. Allow to stand at

ambient temperature for 24 hours or until the moisture content has reduced to at least 50 % of

OMC.

Note: With certain materials lacking cohesion, it may be necessary to leave the specimen in the

mould for 24 hours, allowing sufficient strength to develop before extracting.


Appendix 3: Strength Test Procedures

3.1 Determination of Indirect Tensile Strength (ITS)

The ITS test is used to test the briquettes under different moisture conditions including dry, soaked

and equilibrium moisture content. The ITS is determined by measuring the ultimate load to failure

of a briquette that is subjected to a constant deformation rate of 50.8 mm/minute on its diametrical

axis. The procedure is as follows:

STEP 1

Place the briquette onto the ITS jig. Position the sample such that the loading strips are parallel

and centred on the vertical diametrical plane.

STEP 2

Place the load transfer plate on the top bearing strip and position the jig assembly centrally under

the loading ram of the compression testing device.

STEP 3

Apply the load to the briquette, without shock, at a rate of advance of 50.8 mm per minute until

the maximum load is reached. Record the maximum load P (in kN), accurate to 0.1 kN.

STEP 4

Immediately after testing a briquette, break it up and take a sample of approximately 1000 g to

determine the moisture content (Wbreak). This moisture content is used to determine the dry

density of the briquette.

STEP 5

Calculate the ITS for each briquette to the nearest 1 kPa using equation

ITS = (2 x P) / (∏ x h x d) x 10000

Where: ITS = indirect tensile strength [kPa]

P = maximum applied load [kN]

h = average height of the specimen [cm]

d = diameter of the specimen [cm]

STEP 6

To determine the soaked ITS, place the briquettes under water at 25 °C ± 1 °C for 24 hours.

Remove briquettes from water, surface dry and repeat steps 1 to 5.

The “Tensile Strength Retained (TSR)” is the relationship between the soaked and un-soaked ITS


for a specific batch of briquette specimens, expressed as a percentage using equation

TSR = Soaked ITS / Un-soaked ITS x 100


3.2 Indirect Tension Test for Resilient Modulus of Bituminous mixtures :( ASTM D 4123-82) Summery of test method

• The repeated load indirect tension test for determining resilient modulus of bituminous

mixtures is conducted by applying compressive loads with a haversine or other suitable

wave form. The load is applied vertically in the vertical diametrical plane of a cylindrical

specimen of asphalt concrete. The resulting horizontal deformation of the specimen is

measured and with an assumed Poisson’s ratio, is used to calculate a resilient modulus. A

resilient Poisson’s ratio can also be calculated using the measured recoverable vertical and

horizontal deformations.

• Interpretation of the deformation data as resulted in two resilient modulus values being

used. The instantaneous resilient modulus is calculated using the recoverable deformation

that occurs instantaneously during the unloading portion of one cycle. The total resilient

modulus is calculated using the total recoverable deformation which includes both

instantaneous recoverable and the time dependent continuing recoverable deformation

during the unloading and rest-period portion of one cycle.

Significance and use:

• The values of resilient modulus can be used to evaluate the relative quality of materials as

well as to generate input for pavement design or pavement evaluation and analysis. The

test can be used to study effects of temperature, loading rate, rest periods etc. since the

procedure is non-destructive, tests can be repeated on a specimen to evaluate conditioning

as with temperature or moisture. This test method is not intended for use in specifications.


_________________________________________CHAPTER - 7

7. REFERENCES Websites

1. www.asphalt.csir.co.za

2. www.arra.org

3. www.infra.com

4. www.wirtgen.com

Reports and papers

1. Wirtgen cold recycling manual-2004

2. Wirtgen job reports

3. Dr. Bose.S, Dr. Sangita, M.P. singh & Girish Sharma “Use of cold mix recycling for

rehabilitation of flexible pavements"

4. CAPSA'99 - Muthen et al: Foamed Asphalt Mixes Mix Design Procedure

5. Ramanujam, J.M. & Fernando, D.P. 1997. Foam Bitumen Trial at Gladfield-Cunningham

Highway. In: Proceedings of the Southern Region Symposium, Australia, 1997.

6. A Basic asphalt emulsion manual “Manual Series No.19” third edition

7. TRL Report TRL645 “Feasibility of recycling thin surfacing back in to thin surfacing

systems”

8. CAPSA'99 - Jenkins et al: Characterisation Of Foamed Bitumen

9. CAPSA'99 - Engelbrecht: Manufacturing Foam Bitumen In A Standard Drum Mixing

Asphalt Plant

10. Capsa'99 - Lewis: Cold In Place Recycling: A Relevant Process For Road Rehabilitation

And Upgrading

11. Acott, S.M. & Myburgh, P.A. 1983. Design and performance study of sand bases treated

with foamed asphalt. In: Low-volume roads: third international conference. Washington,

DC: (Transportation Research Record; 898), pp 290-296.

12. Acott, S.M.1979. Sand stabilisation using foamed bitumen. In: 3rd Conference on Asphalt

Pavements for Southern Africa, 3rd, 1979, Durban, pp.155-172.


13. Akeroyd, F.M.L. & Hicks, B.J. 1988. Foamed Bitumen Road Recycling. Highways,

Volume 56, Number 1933, pp 42, 43, 45.

14. Akeroyd, F.M.M. 1989. Advances in foamed bitumen technology. In: Fifth conference on

asphalt pavements for Southern Africa; CAPSA 89, held in Swaziland, 5-9 June 1989,

Section 8, pp 1-4

15. Bissada, A.F. 1987. Structural response of foamed-asphalt-sand mixtures in hot

environments. In: Asphalt materials and mixtures. Washington, DC: Transportation

Research Board. (Transportation Research Record, 1115), pp 134-149.

16. Bowering, R.H. & Martin, C.L. 1976. Foamed bitumen production and application of

mixtures, evaluation and performance of pavements. in: Proceedings of the Association of

Asphalt Paving Technologists, Vol. 45, pp. 453-477.

17. Bowering, R.H. 1970. Properties and behaviour of foamed bitumen mixtures for road

building. In: Proceedings of the 5th Australian Road Research Board Conference, held in

Canberra, Australia, 1970, pp. 38-57.

18. Bowering, R.H. & Martin, C.L. 1976. Performance of newly constructed full depth foamed

bitumen pavements. In: Proceedings of the 8th Australian Road Research Board

Conference, held in Perth, Australia, 1976.

19. Brennen, M., Tia, M., Altschaeffl, A.G. & Wood, L.E. 1983. Laboratory investigation of

the use of foamed asphalt for recycled bituminous pavements. In: Asphalt materials,

mixtures, construction, moisture effects and sulfur. Washington, DC: Transportation

Research Board. (Transportation Research Record; 911), pp 80-87.

20. Castedo-Franco, L.H., Beaudoin, C.C., Wood, E.L. & Altschaeffl, A.G. 1984. Durability

characteristics of foamed asphalt mixtures. In: Proceedings of the 29th Annual Canadian

Technical Asphalt Association Conference, held in Montreal, Canada, 1984.

21. Collings, D. 1997. Through foaming it's possible to mix hot asphalt with cold, damp

aggregate. Asphalt Contractor, June 1997 (Article based on the presentation at the 1997

ARRA annual meeting, San Antonio, TX).

22. Joubert, G., Poolman, S. & Strauss, P.J. 1989. Foam bitumen stabilised sand as an

alternative to gravel bases for low volume roads. In: 5th Conference on Asphalt Pavements

for South Africa (CAPSA 89), Proceedings held in Swaziland, 5-9 June, 1989, Section 8,

pp21-5.


23. Lancaster. J., McArthur, L. & Warwick, R. 1994. VICROADS experience with foamed

bitumen stabilisation. In: 17th ARRB Conference, Proceedings held in Gold Coast,

Queensland, 15-19 August, 1994, Volume 17, Part 3, pp193-211.

24. Lee, D.Y. 1981. Treating marginal aggregates and soil with foamed asphalt. In:

Proceedings of the Association of Asphalt Paving Technologists, Vol. 50, pp 211-150.

25. Little, D.N., Button, J.W. & Epps, J.A. 1983. Structural properties of laboratory mixtures

containing foamed asphalt and marginal aggregates. In: Asphalt materials, mixtures,

construction, moisture effects, and sulfur. Washington, DC: Transportation Research

Board. (Transportation Research Record; 911), pp 104-113.

26. Maccarrone, S., Holleran, G., Leonard. D.J. & Hey, S. 1994. Pavement Recycling using

Foamed Bitumen. In: 17th ARRB Conference, Proceedings held in Gold Coast,

Queensland, 15-19 August, 1994, Volume 17, Part 3, pp 349-365.

27. Maccarrone, S., Holleran, G, & Leonard, D.J. 1993. Bitumen Stabilisation - A New

Approach To Recycling Pavements. In: AAPA Members Conference, 1993.

28. Maccarrone, S., Holleran, G. & Ky, A. 1995. Cold Asphalt Systems as an Alternative to

Hot Mix. In: 9th AAPA International Asphalt Conference.

29. Roberts, F.L., Engelbrecht, J.C. & Kennedy, T.W. 1984. Evaluation of recycled mixtures

using foamed asphalt. In: Asphalt mixtures and performance. Washington, DC:

Transportation Research Board. (Transportation Research Record; 968), pp 78-85.

30. Foamix asphalt advances by Ruckel, P.J. ... [et al]. In: Asphalt Pavement Construction:

New Materials and Techniques. Philadelphia, PA: American Society for Testing and

Materials (ASTM STP; 724), pp. 93-109.

31. Ruckel, P.J., Acott, S.M. & Bowering, R.H. 1982. Foamed-asphalt paving mixtures:

preparation of design mixes and treatment of test specimens. In: Asphalt materials,

mixtures, construction, moisture effects and sulfur. Washington, DC: Transportation


32. Sakr, H.A. & Manke, P.G. 1985. Innovations in Oklahoma foamix design procedures. In:

Asphalt materials, mixes, construction and quality. Washingtong, DC: Transportation

Research Board. (Transportation Research Record;1034), pp 26-34.

33. Tia, M. & Wood, L.E. 1983. Use of asphalt emulsion and foamed asphalt in cold-recycled

asphalt paving mixtures. In: Low-volume roads: third international conference.


Washington, DC: Transportation Research Board. (Transportation Research Record; 898),

pp 315-322.

34. Van Wyk, A., Yoder, E.J. & Wood, L.E. 1983. Determination of structural equivalency

factors of recycled layers by using field data. In: Low-volume roads: third international

conference. Washington, DC: Transportation Research Board. (Transportation Research

Record; 898), pp 122-132.

35. Van Wijk, A.J. 1984. Structural comparison of two cold recycled pavement layers. In:

Design, evaluation, and performance of pavements. Washington, DC: Transportation


36. Van Wijk, A. & Wood, L.E. 1983. Use of foamed asphalt in recycling of an asphalt

pavement. In: Asphalt materials, mixtures, construction, moisture effects and sulfur.

Washington, DC: Transportation Research Board. (Transportation Research Record; 911),

pp 96-103.

37. Van Wijk. A. & Wood, L.E. 1982. Construction of a recycled pavement using foamed

asphalt. In: Proceedings of the Twenty-seventh Annual Conference of Canadian Technical

Asphalt Association, edited by P Turcotte, held in Edmonton, Alberta, Canada, 1982.

38. CAPSA'99 - van der Walt et al: The Use Of Foamed Bitumen In Full-Depth In-Place

Recycling Of Pavement Layers Illustrating The Basic Concept Of Water Saturation In The

Foam Process

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Lab and field eveluation of recycled cold mix

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