Test Procedures/Methodologies for Reclaimed Asphalts Binder

End of life strategies of asphalt pavementsRe - Road

Test Procedures/Methodologies for Reclaimed Asphalts Binder Virginie Mouillet et al.

The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007–2013) under grant agreement n° 218747.

Re - RoadRoadDeliverable 1.4 WP1 0.2

“Test procedures/methodologies for Reclaimed Asphalts binder”

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Grant SCP7-GA-2008-218747

Authors: WP1 File: Re-road_ D1.4_v0.1_co_27August12.doc

Re-Road – End of life strategies of asphalt pavements

Deliverable 1.4


EUROPEAN COMMISSION DG RESEARCH

A FP7 Collaborative Project Work programme: Sustainable Surface Transport SST.2007.1.2.2 End of life strategies for vehicles/vessels and infrastructures



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Executive summary

As binder extraction and recovery is an essential step to determine the basic characteristics of RA, the impact of the couple testing method/solvent on the binder content and binder characteristics has been assessed in the frame of a comparative study of different standardized methods according to the European test methods EN 12697-1 and EN 12697-3 applied to RA with PmB.

The six laboratories involved in task 1.2 have participated in a round robin test, in which two freshly produced asphalt mixtures and two artificial RA produced in laboratory (with exactly known binder content and binder properties) were tested. As the standards describe a large range of methods and solvents that can be chosen to carry out the extraction and recovery tests, the different results have been compared to the “true” properties in order to evaluate the adequacy of the methods and solvents proposed in standards for the right characterization of RA with PmB.

This experimental campaign have been performed on two kinds of asphalt mixes: one “standard mix with unmodified binder“ as reference (called “AC11”) and one PmB modified mix with “standard” PmB (called “MR”) before and after laboratory ageing. The binder used to produce the unaged and aged MR mixes was announced as modified with SBS. However, the analysis by Fourier Transform InfraRed spectroscopy has revealed that binders from MR mixes are not modified by polymer as originally supposed (not visualized by consistency tests). Consequently, the initial objective to select suitable experimental parameters in order to obtain the correct binder content and the correct properties of PmB in RA could not be reached. But, comparing to the results of the 2 actual RA (called PRA and RA (V1)) described in deliverable D1.2, the soluble binder content results of the 2 artificial RA are less scattered around the mean value with low standard deviations and variation coefficients. It seems that problems appear for actual RA with PmB, for which the ageing level of the bitumen in the RA is more intense and combined with the presence of polymers leads to a more difficult recovery. The round robin tests session on two artificial RA led to interesting results about the gap between the true value and the measurement that is more important for MR mixes than for AC11 mixes. It showed also the impact of the solvent on the tests results:

For AC11 mix aged, Toluene seems to be the best solvent.

For MR mix aged, Trichlorethylen seems to be better.

However, number of participating laboratories and repetitions was limited, so this result needs to be confirmed in the future by a similar round robin test but at a larger scale: more participants and more repetitions.



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Concerning the characteristics of the recovered binders that have consisted in measurement of usual properties of a binder (penetration, softening point) and laboratory assessment of the quality, nature and ageing level of a bituminous binder (oxidation degree, polymer content, complex modulus, ductility force, elastic recovery), only two of them have permitted to differentiate the 2 actual RA :

content of carbonyls (more important due to the oxidative ageing),

complex modulus at 25 and 52°C (higher due to the hardening of binder).

It means that these two characteristics are relevant to assess the end of life (binder state) of binders and could be used for the choice of adding binder (as indicators for the recyclability potential of aged binder). In the future, it would be interesting to define the threshold values of these characteristics for recycling a RA. This can be done only by collecting data.

To conclude, the European standards EN 12697-1 and EN 12697-3 appear not clear enough when asphalt contains PmB. In the future, it seems very important to focus research on 2 key issues:

characterization and technical evaluation of RA containing modified binders in order to assess their capability to be recycled, in particular to mix with the fresh added bitumen.

degradation process of the polymers in asphalt layers with modified bitumen in order to understand how to restore the polymeric modification during recycling.

Virginie Mouillet, WP1 leader Marc-Stéphane Ginoux Nathalie Piérard Konrad Mollenhauer Thomas Gabet Krzysztof Mirski Ema Kemperle

Re - RoadRoadDeliverable 1.4 WP1 0.2.


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Table of contents

1 Introduction .................................................................................................... 9

2 State of the art on extraction and recovery of binder in RA ..................... 10 2.1 European standards .................................................................................... 10 2.1.1 Presentation of European standard EN 12697-1 ”Soluble binder content” ...................................................................................................................... 10 2.1.2 Presentation of European standard EN 12697-3 ”Bitumen recovery : rotary evaporator” ...................................................................................................... 12 2.2 National experimental procedures described in the literature ................ 13 2.2.1 European standard EN 12697-1 ”Soluble binder content” in case of polymer-modified bitumen ......................................................................................... 13 2.2.2 European standard EN 12697-3 “Bitumen recovery with a rotary evaporator” in case of polymer-modified bitumen ...................................................... 14

3 Laboratory characterization of bitumen part of Reclaimed Asphalts ...... 16 3.1 Selected samples and preparation in laboratory of artificial Reclaimed Asphalts ................................................................................................. 16 3.2 Determination of the soluble binder content in bituminous mixtures according to EN 12697-1 (April 2006) .................................................................... 20 3.2.1 Repeatability study on AC11 ......................................................................... 20 3.2.2 Results and interpretation .............................................................................. 22 3.2.3 Global interpretation of the results ................................................................. 24 3.2.4 Conclusions ................................................................................................... 26 3.3 Determination of the characteristics of recovered PmB .......................... 27 3.3.1 Presentation of characterization methods ..................................................... 27 3.3.2 Results of penetration measurements ........................................................... 31 3.3.3 Results of Ring & Ball temperature measurements ....................................... 33 3.3.4 Results of oxidation degree ........................................................................... 36 3.3.5 Results of polymer content ............................................................................ 38 3.3.6 Results of complex modulus and phase angle .............................................. 40 3.3.7 Results of ductility force and elastic recovery ................................................ 44 3.3.8 Choice of relevant indicators for recyclability potential’s assessment ........... 47

4 Conclusions ................................................................................................. 49

5 References .................................................................................................... 52

Tables



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Table 1 : EN- methods for determination of the soluble binder content described in EN 12697-1 (version of April 2006) and their use by each partner .................................................................................................... 12

Table 2 : Temperature and pressure applied for binder recovery according to EN 12697-3 (June 2005) ................................................... 13

Table 3 : Mix design composition of AC11 unaged and aged ................ 18

Table 4 : Mix design composition of MR-0A0 and MR-RA1 ................... 19

Table 5 : statistical analysis of binder contents obtained ....................... 22

Table 6 : Binder contents of the two “artificial” RA ................................. 23

Table 7 : Statistical analysis of binder contents ..................................... 24

Table 8 : Penetration at 25°C (1/10 mm) of the recovered binder .......... 31

Table 9 : Main results of the penetration at 25°C measured for each material .................................................................................................. 31

Table 10 : Softening point values of the recovered PmB for each material tested ..................................................................................................... 33

Table 11 : Main results of the softening point measured for each material ............................................................................................................... 34

Table 12 : Oxidation characteristics of the recovered PmB for each material tested ....................................................................................... 37

Table 13 : Main results of the carbonyl content measured for each material .................................................................................................. 37

Table 14 : Main results of the sulfoxide content measured for each material .................................................................................................. 37

Table 15 : Main results of the oxidation state measured for each material ............................................................................................................... 38

Table 16 : Intensity of polymer peak of the recovered PmB for each material tested ....................................................................................... 39

Table 17 : Main results of the stryrene presence measured for each material .................................................................................................. 39

Table 18 : Main results of the butadiene presence measured for each material .................................................................................................. 40

Table 19 : Rheological characteristics of the recovered PmB for each material tested ....................................................................................... 41

Table 20 : Main results of the rheological parameters measured for AC11 mix ......................................................................................................... 42

Table 21 : Main results of the rheological parameters measured for MR mix ......................................................................................................... 43



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Table 22 : Results of force ductility an elastic recovery tests. ................ 45

Table 23 : Main results of the maximum force FMax, obtained from force ductility tests. ......................................................................................... 46

Table 24 : Main results of the deformation energy obtained between 0 and 200 mm ductility E0,2, obtained from force ductility tests. ................ 47

Table 25 : Evolution of characteristics during artificial ageing and comparison with actual materials. .......................................................... 48

Table 26 : Statistical analysis of soluble binder contents ....................... 49

Figures

Figure 1: aggregates grading of MR and AC mixes .............................. 20

Figure 2: mean binder content according to the solvent........................ 25

Figure 3: FTIR spectra of MR- RA1 recovered binders dissolved in CCl4. ............................................................................................................... 30

Figure 4: Deviation of penetration values of each binder samples from overall mean. ......................................................................................... 32

Figure 5: Mean Penetration for applied extraction methods (results of samples discussed in D1.2 added). ....................................................... 32

Figure 6: Deviation of ring & ball softening temperature values of each binder samples from overall mean. ........................................................ 35

Figure 7: Mean ring & ball temperature for applied extraction methods (results of samples discussed in D1.2 added). ....................................... 36

Figure 8: Course of ductility force versus ductility (left: AC unaged, right: AC aged). ............................................................................................... 45

Figure 9: Deviation of the measured maximum force FMax from the mean values. .................................................................................................... 46



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List of abbreviations AC Asphalt Cement

ARA Asphalt containing Reclaimed Asphalts

BC2 Bucklet centrifuge type 2

CFC Continuous Flow Centrifuge

DCM Dichloromethane

EVA Ethylene-Vinyl Acetate

FTIR Fourier Transform Infra-Red spectroscopy

PA Porous Asphalt

PCE Perchloroethylene

PmB Polymer modified Bitumen

RA Reclaimed Asphalts

R&B Softening point

SBS Styrene-Butadiene-Styrene

SMA Stone Mastic Asphalt

TCE Thrichloroethylene

Tol Toluene

TR&B Ring&Ball Temperature



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1 Introduction

One of the objectives of the Re-Road project is to allow the development of techniques for increasing the recycling rates of Reclaimed Asphalts (RA). However, RA are complex materials and the use of significant proportions of RA in new asphalts involves a more accurate control of their characteristics. These last ones are essential for asphalt mix design and a key factor for correct performance of new asphalt mixtures including a certain percent of RA. Consequently, it is very important to focus on issues that are specifically related to the characterization and technical evaluation of RA and particularly RA containing modified binders for which there is clearly a lack of knowledge and adequate test methods to sample and to analyse them (as shown in deliverable D1.1). One of the topical problem is related with the determination of the binder content for which the present European test methods for extraction and recovery of binder in RA are only normative for RA with pure binders and give only indicative informative for RA containing PmB. A key point for RA containing PmB is to know if the used whole recovery procedure permit to fully extract PmB and to modify as little as possible the properties of PmB or to identify the impact of extraction procedure on the PmB properties as well.

As binder extraction and recovery is a essential step to determine the basic characteristics of RA, the impact of the couple testing method/solvent on the binder content and binder characteristics has been assessed in the frame of a comparative study of different standardized methods according to the European test methods EN 12697-1 and EN 12697-3 applied to RA with PmB. The six laboratories involved in task 1.2 have participated in a round robin test, in which three different bituminous materials have been evaluated: one Stone Mastic Asphalt including 15% of RA and 2 others RA with physical and cross-linked elastomer modified bitumens. The exploitation of this round robin test is described in deliverable D1.2. According to obtained results in this preliminary study, there is no impact of the couple testing method/solvent for the determination of the soluble binder content on a fresh asphalt mixture with modified bitumen and including a low content of RA. Problems appear for RA with PmB, for which the ageing level of the bitumen in the RA, combined with the presence of polymers leads to a more difficult recovery. So, the European standards EN 12697-1 and EN 12697-3 appear not clear enough when asphalt contains PmB. The same trends can be observed on the characteristics of recovered PmB, the values being more scattered for RA than for new mix, whatever the measured properties.

In concordance with these conclusions of deliverable D1.2, it was decided to carry on with the validation step of extraction procedures. The aim of this study was to identify suitable experimental parameters (solvent, methods and temperature of dissolution) to improve the determination of soluble binder content of RA containing PmB and the recovery of PmB for further characterization. Consequently, the proposed experimental strategy consisted in producing in



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laboratory artificial RA with exactly known binder content and binder properties and then application of the different recovery methods according to EN 12697-1 and EN 12697-3 standards. As theses standards describe a large range of methods and solvents that can be chosen to carry out the tests, the different results have been compared to the “true” ones in order to evaluate the adequacy of the methods and solvents proposed in standards for the right characterization of RA with PmB. This experimental campaign have been performed on two kinds of asphalt mixes : one “standard mix with unmodified binder“ as reference and one PmB modified mix with “standard” PmB before and after laboratory ageing. The exploitation of the obtained results is described below. The final objective is to select suitable experimental parameters among large range of methods and solvents proposed in European standards in order to obtain the correct binder content and the correct properties of PmB in RA.

2 State of the art on extraction and recovery of binder in RA

2.1 European standards

Current specifications about RA are given in the European standard EN 13108-8 and aim at characterizing them. This characterization is an essential step for asphalt mix design and a key factor for correct performance of new asphalt mixtures including a certain percent of RA. Indeed, these characteristics influence the capability of the RA to be recycled, in particular its capacity to mix with the fresh added bitumen by the exchange of viscosities. It is strongly related to the ageing level of the bituminous binder present in the RA that is currently assessed by laboratory testing after extraction and/or recovery of binder from RA (according to the EN 12697-1 and/or EN 12697-3). However, the present European test methods for extraction and recovery of binder in RA are only suitable for RA with pure binders and give only indicative guidelines for RA containing Polymer modified Bitumens (PmB). As binder extraction and recovery is essential in order to determine the basic characteristics of RA, it is necessary to assess the impact of the different normalized recovery and extraction methods and solvents on the soluble binder content and characteristics of recovered PmB.

2.1.1 Presentation of European standard EN 12697-1 ”Soluble binder content”

The different methods for determining soluble binder content of bituminous mixtures containing road binders are clearly described in the European standard EN 12697-1, but this is not the case for samples containing Polymer modified Bitumens (PmB).



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The dried asphalt mixture is weighted. By using cold or hot solvent flow through the asphalt mix, the bituminous binder is solved and separated from mineral particles. The binder content is calculated by measuring the weight of the obtained aggregates (difference method) or by measuring the weight of the recovered binder after distillation of the solvent.

European standard EN 12697-1 allows different methods for the extraction of the binder. They are to be combined with different methods for separation of the mineral matter. A table (Figure A.1 in the standard) summarizes which methods could be combined. Different solvents have to be used according to differing work safety regulations.

The standard EN 12697-1 allows also the use of an automatic centrifuge if it can be demonstrated that it provides the same results as one of the methods here above (within the limits of the precision given in the standard).

Consequently, each partner has measured the binder content according to its own methods (see Table 1) chosen from EN 12697-1 (version of April 2006). So, the same samples, representative of the considered RA, are tested by different laboratories, with different methods and different solvents.

Standard method : BRRC IBDiM IFSTTAR LR-Aix TUBS ZAG

1. EN-Methods for binder extraction

Hot extractor X X X (1) X (2)

Soxhlet

Bottle rotation machine X (2,3)

Centrifuge extractor

Cold mix dissolution of bitumen by agitation X (2)

Alternative method :

Automatic extraction and centrifuge apparatus X (1) X (1) X

2. EN-Methods for the separation of mineral matter

Continuous flow centrifuge X (2,3) X X X (1) X (2)

Pressure filter

Bucket centrifuge type 1

Bucket centrifuge type 2 X (2)


Automatic extraction and centrifuge apparatus X (1) X (1) X

3. Solvent

Toluene (Tol) X (2) X (2)

Trichlorethylene (TCE) X (1) X (1) X

Dichloromethane (DCM) X (3)

Perchlorethylene (PCE) X X X (1,2)



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Table 1 : EN- methods for determination of the soluble binder content described in EN 12697-1 (version of April 2006) and their use by each partner1

As can be seen, four methods of those described in the standard are used for the binder extraction by the laboratories involved and the continuous flow centrifuge is the most used method for the separation of the mineral matter. Half of the laboratories also use an automatic extraction and centrifuge apparatus. Although some parameters such as pressure or temperature are controlled, the standard EN 12697-1 allows the use of an automatic device if it can be demonstrated that it provides the same results as one of the methods described in Table 1.

Concerning the choice of solvent, four solvents are used in the different partners’ laboratories.

2.1.2 Presentation of European standard EN 12697-3 ”Bitumen recovery : rotary evaporator”

An important step before characterizing binders is the recovery process, that is done by each partners’ laboratory according its method chosen from EN 12697-1 (version of April 2006) (see table 1) and EN 12697-3 (version of June 2005). In fact, EN 12697-3 describes one procedure to recover bitumen from an asphalt mixture. It consists first to separate and to extract the binder from the bituminous mixture by dissolution in an adequate solvent and by the use of a method to separate it from the mineral matter (according to EN 12697-1 standard). In a second step, bitumen is recovered by distillation using a rotary evaporator.

To recover the binder, the methods used for the separation and the extraction of the soluble binder are the same as the ones mentioned in the Table 1 for most of partners involved in this round robin test except for LR-Aix partner for which the binder was extracted from the mixture by dissolution at 30°C in dichloromethane and was separated from the mineral part using a bucket centrifuge type 2.

During recovery, the solvent is distilled from the bituminous binder in order to accelerate the process. This is done by application a vacuum as well as two sets of temperatures dependent on the solvent used as given in Table 2. During a first phase the solvent-binder mix is sucked into the rotary evaporator. When the whole sample is in the device and the distillation of the solvent stopped, the temperature is increased and pressure is decreased to the values given for phase 2. The evaporation is conducted until the distillation stopped visually. The distillation is stopped when no solvent is distilled visually from the sample. If this time takes longer than 10 minutes, the temperature is increased up to T3.

1 Number between brackets associates the EN- methods used for extraction and separation with the solvent used in an complete procedure.



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Solvent boiling temperature

[°C]

phase 1 phase 2

Temperature T1 [°C]

Pressure p1 [kPa]

Temperature T2 [°C]

Pressure p2 [kPa]

Additional temperature

T3 [°C]

Tol 110.6 110 40 160 2.0 180

TCE 87.0 90 40 160 2.0 185

DCM 40.0 45 85 150 1.3 175

PCE 121.0 110 40 160 2.0 180

Table 2 : Temperature and pressure applied for binder recovery according to EN 12697-3 (June 2005)

2.2 National experimental procedures described in the literature

2.2.1 European standard EN 12697-1 ”Soluble binder content” in case of polymer-modified bitumen

As mentioned in the introduction, standard EN 12697-1 includes a number of test methods specifically developed to determine the binder content of bituminous mixtures bound with unmodified bitumens. For mixtures with polymer-modified bitumen (PmB) only an informative annex (Annex D) is available, owing to lack of experience. Among other things, this annex points out:

the importance of the choice of solvent to ensure good solubility of the PmB; the influence of the temperature of the solvent on the effectiveness of the

dissolution; the need, for certain PmB, to perform several washings with the rotating bottle

machine to dissolve all the polymer.

The polymer most often present in reclaimed asphalt is SBS. Therefore, the following state of the art focuses on information available for SBS-type PmB.

A thorough study into the influence of the solvent and the dissolution method on the binder content measured in SBS PmB-bound mixtures prepared in the laboratory or sampled on site was conducted for four years at BRRC (NBN CC-CCN 308, 358, 504, 554). A continuous flow centrifuge was used to separate the mineral component from the dissolved binder. This separation was made after dissolving the binder in toluene or dichloromethane at ambient temperature, by the method described in Section 1.4 (Rotating bottle machine) of Annex B to the standard or by moderate agitation for 16 h. Binder content determination using an automatic centrifuge extractor was investigated as well. The main conclusions from this study can be reported as follows (Piérard, 2011): measured binder content is generally slightly lower than the initial binder content

for mixtures prepared in the laboratory (bulk material or gyratory compacted



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specimens) (Piérard et al., 2010) or sampled from the bulk material in the finisher. On the other hand, this content can be higher than that of the corresponding bulk material and sometimes even higher than the declared binder content in case of core samples taken on site;

measured binder content is affected by the choice of solvent (toluene gives results closer to the initial content than dichloromethane). On the other hand, there is no systematic impact of the method used for dissolution at ambient temperature;

an automatic centrifuge extractor (using trichloroethylene) gives results comparable to those obtained with a “manual” continuous flow centrifuge after the binder has been dissolved in toluene with a rotating bottle machine.

The study also drew attention to the importance: of verifying whether the content of residue on ignition of the recovered binder at

450 °C is lower than 1 % by mass for any modification of the procedure or change in apparatus;

of leaving as little remnants as possible in the storage box containing the bulk sample, and minimizing the loss of aggregates in the centrifugation process. These two requirements are necessary to limit measurement errors.

Before this research project, a study in 2004 (Molenaar et al., 2004; Landa et al., 2006) investigated the possibility of recovering SBS PmB from a bituminous mixture while comparing two techniques (automatic centrifuge and Soxhlet) for extraction with dichloromethane. It concluded that it is not possible to recover 100 % of the PmB with dichloromethane and that extraction capability depends on the time the sample was taken (during mix production, after laying …).

As for reclaimed asphalt containing PmB, we are not aware of any experiments published to date.

2.2.2 European standard EN 12697-3 “Bitumen recovery with a rotary evaporator” in case of polymer-modified bitumen

Methods based on solvent extraction make it possible to recover the binder for characterization. Generally, once the binder has been dissolved it is recovered with a rotary evaporator by the procedure described in EN 12697-3. After recovery, the characteristics of the binder (penetration, softening temperature …) can be determined.

To characterize the binder as present in a mixture laid on site, it is necessary to: extract all of the binder, i.e., including the polymer. For new mixtures containing

SBS PmB, N. Piérard at al. have demonstrated that with toluene or dichloromethane the PmB is generally fully extracted from bulk mixtures, but that



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there could be a loss when extracting it from core samples (Piérard et al., 2010). Two studies (Degeimbre et al., 1986; Choquet et al., 1992) have also confirmed the good solubility of SBS PmB in tetrachloroethylene in a 7.5% by mass concentration;

have the properties of the binder and the dispersion of the polymer in the bitumen matrix modified as little as possible by the whole recovery procedure. A study into the effects of dissolving PmBs and recovering them with a rotary evaporator (Piérard and Vanelstraete, 2009; Piérard, 2011) has shown that: 1. The properties of SBS PmBs change when they are dissolved (in toluene,

trichloroethylene or dichloromethane) and subsequently recovered. This procedure also alters the distribution of the SBS in the bitumen. However, no evidence has been found to date for a specific correlation between variations in properties and observed modifications in structure. This was also pointed out in two earlier publications (Dumont et al., 1996; Klutz et al., 2004).

2. Dichloromethane and toluene cause smaller modifications in properties than trichloroethylene.

Information on the impact of extraction and recovery methods on the properties of the recovered binders can also be found in the literature. For example, a previously mentioned study by BRRC (see section 2.2.1) has shown that: the dissolution method has a systematic impact on the technological properties of

SBS PmBs recovered from bituminous mixtures. This systematic impact remains or not within the range defined by the repeatability limits of the whole recovery procedure depending on the type of aggregates used in the mixture (Piérard, 2012);

the choice of solvent (toluene or dichloromethane) has no systematic impact on the technological properties of recovered SBS PmBs;

it is important to make sure that the residue on ignition of the recovered binder at 450 °C remains smaller than 1 % by mass; if not, the impact on its characteristics may not be negligible.

Furthermore, another study has evaluated different extraction (centrifuge/Soxhlet; toluene, trichloroethylene and dichloromethane) and recovery methods as well as their influence on the properties of the recovered PmBs in case of binders highly modified with SBS (Nöesler et al., 2008). The conclusions are as follows: there is always a remnant of solvent in the recovered binders (demonstrated

when using trichloroethylene), modifying their characteristics; the different methods yield comparable results, with decreasing impacts if the

amount of residual solvent in the recovered sample is very small; the dissolution and recovery of highly modified new PmB have a low impact on

their properties;



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there is some deterioration of PmB (reduction in molecular mass of the polymers) during the preparation of asphalt mixtures in a laboratory, but the properties of the PmB remain clearly superior to those obtained with the pure binder.

We have been unable to find in the literature any study into the impact of extraction and recovery methods on the characteristics of PmB recovered from reclaimed asphalt. However, the results of the studies mentioned above clearly indicate that it would be interesting to investigate this aspect on reclaimed materials containing PmBs. The advanced state of ageing of PmB in reclaimed asphalt may make the extraction process more difficult and not all the methods standardized to date may give similar results.

3 Laboratory characterization of bitumen part of Reclaimed Asphalts

As the composition of RA binder is an important issue related to the possible re-use of RA and in particular its capacity to mix with the fresh added bitumen by the exchange of viscosities, different characteristics were assessed by laboratory testing after recovery of binder from RA (according to the EN 12697-3). These characteristics are strongly related to the assessment of the end of life of RA, namely the physico-chemical state of the binder and its ageing level. Hence, a representative panel of relevant laboratory procedures has been proposed, that consists in measurement of usual properties of a binder (penetration, softening point) and laboratory assessment of the quality, nature and ageing level of a bituminous binder (oxidation degree, polymer content, complex modulus, force ductility, elastic recovery).

3.1 Selected samples and preparation in laboratory of artificial Reclaimed Asphalts

In order to assess the influence of extraction/recovery methods on the binder content and bitumen characteristics of RA and to precise which experimental parameters are the most influent, two artificial RA with exactly known binder content and binder properties have been prepared in laboratory according to the following experimental procedure :

Mixing the asphalt, sampling of « fresh mix ».

Artificial aging, sampling « aged mix ».

In this framework, the laboratory aging protocol consists in aging a loose mix placed in a tray, in an air-draft ventilated oven, according to a short-term aging, 4 hours at 135°C, followed by a long term aging, 9 days at 85°C. This



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procedure is simple and easily reproducible. The only other criterion to respect is that specimen depth must not overpass 8 cm, in order to ensure a certain level of air circulation in the specimen. Results of previous round robin tests performed on this ageing protocol have shown a good reproducibility of this procedure (De La Roche et al., 2009) (De La Roche et al., 2010).

Shipping of « fresh and aged » mixes to recovery partners.

Application of recovery methods and binder tests. It has to be asked to all partners to perform binders recovery in 2 weeks after sending the mixes to limit the difference of aging state between all samples.

Two kinds of asphalt have been selected :

One French classical asphalt concrete named AC11 with pure 35/50 binder (“true” value of binder content intended by mix design = 5,40%). This first asphalt mixture will be used as reference sample because :

o Soluble binder content tests were previously done for hot mix asphalts with pure binder so that all standard method shall be available for this asphalt mixture.

o 35/50 penetration grade bitumen is a very commonly used binder and its ageing has been studied for a long time (De la Roche et al., 2010).

The mix sample AC11 was mixed in laboratory according to the mix design summarised in Table 3. After mixing half of the sample was filled into buckets and shipped to participating laboratories for extraction and recovery of fresh materials. The second half of the mix was aged according to the “RILEM” aging procedure by storing loose mixes on a plate for 9 days at a temperature of 85 °C as also applied during Re-Road-project in work package 2 (see deliverable D2.3). After aging the sample was filled into buckets and labelled as “AC11 aged” for binder extraction and recovery of aged materials.

Mix design composition

AC11 unaged and aged

Composition of aggregate fractions

(100 % = aggregate mass) [%]

Filler (limestone) 1

0/2 (quarry bréfauchet) 34

2/6.3 (quarry bréfauchet) 16

5.6/11.2 (quarry bréfauchet) 49

Grading of resulting mix


d < 0.063 6.8



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0.063 ≤ d < 0.125 3.0

0.125 ≤ d < 0.25 3.0

0.25 ≤ d < 1.0 8.0

1.0 ≤ d < 2.0 9.6

2.0 ≤ d < 5.6 28.5

5.6 ≤ d < 8.0 13.8

8.0 ≤ d < 11.0 16.5

d > 11.0 10.8

Binder

Type of binder Pure binder 35/50

Asphalt mix composition

(100 % = total asphalt mix) [%]

Total binder content 5.40

Table 3 : Mix design composition of AC11 unaged and aged

One German classical stone mastic asphalt (SMA) named MR-0A0 with Polymer modified Bitumen (“true” value of binder content intended by mix design = 7.00%). The mix sample MR-0A0 was mixed in laboratory according to the mix design summarised in Table 4. After mixing half of the sample was filled into buckets and shipped to participating laboratories for extraction and recovery of fresh materials. The second half of the mix was aged according to the “RILEM” aging procedure by storing loose mixes on a plate for 9 days at a temperature of 85 °C as also applied during Re-Road-project in work package 2 (see deliverable D2.3). After aging the sample was filled into buckets and labelled as “MR-RA1” for binder extraction and recovery of aged materials.

Mix design composition

MR-0A0 and MR-RA1

Composition of aggregate fractions


Filler (limestone) 8.4

0/2 (gabbroid) 18.3

2/5 (gabbroid) 23.1

5/8 (gabbroid) 47.0

8/11 (gabbroid) 2.9

Fibres (Viatop) 0.3



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Grading of resulting mix


d < 0.063 9.0

0.063 ≤ d < 0.125 2.8

0.125 ≤ d < 0.25 2.7

0.25 ≤ d < 1.0 6.2

1.0 ≤ d < 2.0 6.3

2.0 ≤ d < 5.6 23.2

5.6 ≤ d < 8.0 47.1

8.0 ≤ d < 11.0 2.7

d > 11.0 0

Binder

Type of binder 25/55-55 (chemically linked)

Asphalt mix composition

(100 % = total asphalt mix) [%]

Total binder content 7.00

Table 4 : Mix design composition of MR-0A0 and MR-RA1

One can note that the grading curves of the two kinds of mixes (see Figure 1) correspond to two commonly used asphalt concrete in France and Germany:

AC11 has the granularity of French “Béton Bitumineux Semi-Grenu” (BBSG). which is an asphalt concrete dedicated to wearing or binder course. usually designed with :

o a percentage of fine elements between 6.5% and 7.5%;

o a percentage of passing elements at 2 mm between 30% and 35%;

o a percentage of passing elements at 6.3 mm close to 60 %.

MR-0A0 and MR-RA1 has the granularity of a German Stone Mastic Asphalt (SMA) usually applied as a surface course for heavy trafficked flexible pavements in a thickness of up to 4 cm. The specifications on this type of mix are as followed:

o a percentage of filler between 8 % an 12 %;

o a percentage of passing grains at 2 mm between 20 % and 30 %;

o a percentage of passing grains at 5.6 mm between 35 % and 55 %.



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0

20

40

60

80

100

1,E‐02 1,E‐01 1,E+00 1,E+01

Passing (%

)

Sieve (mm)

Aggregates grading of MR 0A0 and MR RA1

Aggregates grading of AC11

Figure 1: aggregates grading of MR and AC mixes

3.2 Determination of the soluble binder content in bituminous mixtures according to EN 12697-1 (April 2006)

3.2.1 Repeatability study on AC11

An experimental study was performed in order to assess the repeatability of measurement of soluble binder content. This study was carried out by only one laboratory, IFSTTAR, on one soluble binder content method (method using the Asphalt Analysator), and on one material, the AC11.

It has to be noted here that this repeatability study was initially performed in order to partially validate the method developed at IFSTTAR using the Asphalt Analysator and tetrachloroethylene. Until 2010, a manual method for the determination of soluble binder content was used. It has been replaced by an automatic one for health and safety matters.

This study completes a round robin test carried out in France in 2011 on reclaimed asphalt [EAPIC, 1st campaign, 4th session, serie n°10]. This test involved 43 laboratories. It showed that the Asphalt Analysator apparatus was fully able to determine a binder content, according to the results of all the laboratories included in the round robin test.

The following results give an order of magnitude of the repeatability of the soluble binder content method.



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3.2.1.1 Experimental conditions

The material has not been compacted. only the loose mix is considered. 2 batches of 30 kg have been manufactured:

the first one called “AC11 non aged” has been immediately sampled and stored in impervious paper bags of 3 kg each.

the second batch has been aged according to the RILEM TC-ATB TG5 aging protocol (De la Roche et al., 2010).

The repeatability study includes the determination of the soluble binder content and the sampling. The samples are not strictly identical because of the bias induced by manufacturing and quality of mixing. Nevertheless, they can be considered as identical as they have been done according to the same process in conditions of repeatability (according to standard ISO 5725-1): identical test items, same operators, same equipment within short interval of time

3.2.1.2 Results

The binder content results are presented in Table 5. As observed in this table, the difference between the “real” mean value (controlled during manufacturing) and the measured mean binder content value is negligible, whatever the batch (5.40% instead of 5.42% for the two batches). It represents a relative error of 1% of the real binder content mean value. Thus, it can be concluded that a high number of measurement leads to a good measure of the binder content, and that a measurement performed on the all batch gives the good binder content, with less than 1% of error. As results are the same for non aged and aged materials, it can also be concluded that the age of the binder does not influence the results. If all measurements are considered and compared, a relative discrepancy can be observed in terms of results. Indeed, spans of 0.49% and 0.55% of binder content can be observed, which represent a relative span of 10% of the mean value. This is ten times more than the difference between the measured and the real mean binder content value.

Finally, it can be concluded that for this material and this method, the precision of the soluble binder content given by our apparatus is of 99.63% (0.37% or relative error) by using ten repetitions. As the mean value is very near of the “true value”, it seems that the main error is caused by sampling, not by the method itself.

This test gives an order of magnitude of the discrepancy that can be observed for well controlled and classical asphalt concrete samples when soluble binder content is assessed. Thus, finding such a discrepancy between results performed on different samples should not be considered as surprising when studying reclaimed asphalt.



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Unfortunately, at this time, these results can not be extended to other methods and materials.

Sample AC11 Binder content (%)

unaged aged

N°1 5.62 5.39 N°2 5.50 5.50 N°3 5.57 5.45 N°4 5.68 5.21 N°5 5.32 5.14 N°6 5.20 5.50 N°7 5.19 5.52 N°8 5.44 5.69 N°9 5.27 5.19 N°10 5.39 5.65

True mean 5.40 5.40 Measured mean (m) 5.42 5.42

Error 0.02 0.02 Relative error 0.37% 0.37%

Maximum 5.68 5.69

Minimum 5.19 5.14

Span 0.49 0.55

Relative span 9% 10% Standard Deviation (sd) 0.17 0.19

Variation Coefficient (sd/m) 3.1% 3.5%

Table 5 : statistical analysis of binder contents obtained

on 20 (2*10) samples taken on 2 batches

3.2.2 Results and interpretation

Due to the quantity of materials available. only the binder content of the AC11 mixes has been measured with 2 repetitions.



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Standard method EN 12697‐1 (April

2006):

BRRC (1)

BRRC (2)

BRRC(3)

IBDiM IFSTTAR LR Aix (2) TUBS (1)

TUBS(2)

ZAG

1. EN‐Methods for binder extraction

Hot extractor (part B.1.2) X X X

Soxhlet (part B.1.3)

Bottle rotation machine (part B.1.4) X X

Centrifuge extractor (part B.1.5)

Cold mix dissolution of bitumen by agitation (part B.1.6)

X

Dissolution of binder in the automatic centrifuge at room temperature (using a washing chamber and a rotating sieve drum)

X

Automatic extractor & recovery (part B.1.2 + part B.2.1)

X X

Solvent TCE Toluene DCM PCE PCE PCE TCE Toluene TCE

2. EN‐Methods for the separation of mineral matter

Continuous flow centrifuge (part B.2.1)

X X X X X

Pressure filter (part B.2.2)

Bucket centrifuge type 1 (part B.2.3)

Bucket centrifuge type 2 (part B.2.4) X


Automatic centrifuge X X X

3. EN‐Methods for the determination of soluble binder quantity

Difference method (part 5.4.2.1) X X X X X (*) X (*)

Recovery method (part 5.4.2.2) : total recovery (a) or recovery from portion (volume (b) or mass (c) calculation)

X X(c) X(a) (**) X(a) (**)

4. RESULTS

AC11 unaged 1st repetition 5.41% 5.44% 5.33% 5.60% 5.66% 5.80% 5.36% (*) 5.63% (*) 5.39%

2nd repetition 5.39% 5.32% 5.48% 5.77% 5.42% 5.68% 5.19% (**) 5.51% (**) 5.46%

AC11 aged

1st repetition 5.53% 5.30% 5.30% 5.92% 5.05% 5.51% 5.54% (*) 5.30% (*) 5.64%

2nd repetition 5.58% 5.22% 5.17% 5.71% 5.42% 5.78% 5.62% (**) 5.28% (**) 5.77%

MR‐OAO unaged

1st repetition 6.93% 6.56% 6.46% 6.86% 7.36% 6.69% 6.74% 6.65% 6.78%

MR‐RA1 aged

1st repetition 6.82% 6.49% 6.58% 6.78% 7.04% 6.64% 6.84% 6.91% 6.83%

(Note: PCE means perchlorethylene. TCE means trichlorethylene and DCM means dichloromethane)

(* : determination of soluble binder content done according to difference method

** : determination of soluble binder content done according to total recovery method)

Table 6 : Binder contents of the two “artificial” RA



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3.2.3 Global interpretation of the results

A statistical analysis of the results leads to the following data:

AC11 unaged AC11 aged MR-OAO unaged

MR–RA1 aged

“True value” (mix design) 5.40 5.40 7.00 7.00

Mean 5.49 5.48 6.78 6.77

Error 0.09 0.08 -0.22 -0.23

Standard Deviation 0.17 0.24 0.26 0.17

Minimum 5.19 5.05 6.46 6.49

Maximum 5.80 5.92 7.36 7.04

Span 0.61 0.87 0.90 0.55

repeatability (r) 0.28 0.36

Reproducibility (R) 0.47 0.68 0.73 0.48

Uncertainty U (k=2) 0.20 0.34

Table 7 : Statistical analysis of binder contents

The repeatability and reproducibility were calculated according to standard ISO 5725-2.

To evaluate the effect of solvent used during extraction and recovery, Figure 2 shows the mean values calculated from the binder content values obtained by using the different solvents. The total range of binder content values is indicated by error bars.



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Figure 2: mean binder content according to the solvent

For the tests performed on the AC 11, the following properties can be observed:

Whatever the method of extraction and solvent are, the uncertainty is higher when the asphalt concrete is aged (see Table 7).

The true value of the binder content is 5.40%. Both tests sessions leads to higher binder content, and it is principally due to the results obtained with perchloroethylen which get the higher values and generate the higher gap between the measured binder content and the true binder content.

The binder content tends to decrease when the asphalt concrete is aged (see Figure 2). It could be due to a lower solubility of the aged binder. It can also explain that for the aged binder the repeatability and reproducibility are higher that the ones given in the EN 12697-1.

The repeatability and the reproducibility of the test performed on the unaged AC 11 are similar to those given in standard EN 12697-1 article 8.1 (r = 0.3% and R = 0.5% for the first experiment, article 8.1); but taking into account the fourth experiment (r=0.23% and R = 0.31%) for which the results of 41 participants were statistically analysed (and 6 laboratories rejected), the obtained precision values are higher, probably explained by the low number of involved laboratories (6).

Toluene gives the results the nearest of the “true value” with a relatively low standard deviation.

The test session on the German SMA provides different results. There is not a sufficient amount of test results to calculate the repeatability but it can be observed the following elements:



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The results are less scattered when the aged SMA is tested excepted for toluene.

There is no significant difference on the measured binder content between the aged and the unaged SMA, but both mean values are far from the true value (7.00%). The gap between the true value and the measurement is more important than for the AC 11 with pure bitumen.

Mean value determined with Perchlorethylene on the unaged asphalt are very close to the true value (6.97 % for 7.00 %) but higher scatter is observed.

The reproducibility of the test performed on aged and the unaged SMA are significantly higher compared to the one given in the fourth experiment of standard EN 12697-1 (R = 0.31%) for which the results of 41 participants were statistically analysed (and 6 laboratories rejected), that can be probably explained by the low number of involved laboratories (6).

Trichloroethylene gives the results the nearest of the “true value” with a relatively low standard deviation

In order to decrease the measurement error of soluble binder content, it has been demonstrated (Piérard, 2012) that it is very important:

to be sure of the good solubility of the binder in the chosen solvent,

to check that the residue on ignition (450°C during 8 hours) of the recovered binder has not to exceed 1% of the mass taken; for example, the aged and the unaged SMA recovered by BRRC partner using an automatic centrifuge with Trichloroethylen have shown a residue higher than 1% and could partially explain the obtained values of soluble binder content that are higher than the ones obtained by this partner with other methods and solvents.

to avoid the loss of aggregates during centrifugation step.

3.2.4 Conclusions

The round robin tests sessions led to interesting results and showed the impact of the solvent and the method on the tests results. It also appears that the ageing of bitumen can have an important influence on the tests results, as binder contents values mesured on aged asphalt concretes provided more scattered results.

For a reclaimed asphalt from SMA, Trichlorethylen seems to be better. Meanwhile, the number or participating laboratories and repetitions was to low in order to evaluate significant results. The result obtained in this study should be confirmed by a similar round robin test but at a larger scale : more participants and more repetitions.



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For a reclaimed asphalt from asphalt concrete, Toluene seems to be the best solvent. Even though the number of repetitions is more important than for the RA with PmB, these properties should be confirmed by a larger scale round robin test.

Normally, the study should compare the effects of the choice of extraction methods on binder content for RA containing PmB and for RA with non modified bitumen. But, as analyses has shown at paragraph 3.3.5, the RA from SMA does not contain PmB SBS as scheduled. So further work is necessary to complete the results. The conclusions drawn here above concern only RA with pure bitumen. For RA with PmB the conclusions based on the studied RA from site (described in the deliverable D1.2) are mainly that there is an impact of solvent and extraction methods. This effect depends on the nature of PmB; it is more pronounced for a chemically linked polymer modified bitumen that could be due to some solubility problem linked to the nature and temperature of used solvent.

A key point underlined in this study is that it is very important to check that the residue on ignition (450°C during 8 hours) of the recovered binder has not to exceed 1% of the mass taken; otherwise, there is a bias on the soluble binder content that could be artificially higher. That could be the case when using a manual method as well for an automated method. For a safer working environment in industry, it would be recommended to accept automated method as good as the other method with the condition (as for the other methods) that the residue on ignition (450°C during 8 hours) of the recovered binder do not to exceed 1% of the mass taken.

3.3 Determination of the characteristics of recovered PmB

3.3.1 Presentation of characterization methods

As the composition of RA binder is an important issue related to the possible re-use of RA and in particular its capacity to mix with the fresh added bitumen by the exchange of viscosities, different characteristics have been assessed by laboratory testing after recovery of binder from RA (according to EN 12697-3). These characteristics are strongly related to the assessment of the end of life of RA, namely the physico-chemical state of the binder and its ageing level. Hence, a representative panel of relevant laboratory procedures has been proposed, that consists in measurement of usual properties of a binder (penetration, softening point) and laboratory assessment of the quality, nature and ageing level of a bituminous binder (oxidation degree, polymer content, complex modulus, ductility force, elastic recovery). It has to be noted that, in order to avoid bias effects due to reproducibility



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scattering caused by the test method, one single partner’s laboratory has performed one type of test for all recovered binders.

Then, the impact of the recovery method and solvent used has been assessed on different measured properties that are:

Consistency parameters: measurement of penetration at 25°C (1/10 mm) according to the European standard EN 1426 and ring and ball softening point TR&B (°C) according to the European standard EN 1427.

Oxidation degree: it is determined by Fourier Transform Spectrometry, that measures the InfraRed light absorbed by a material. This absorption will be function of its constituent and particularly of the chemical function present in this material. Technically an infrared light beam is charged through the dissolved material. This energy activates bonds in molecules to vibrate and rotate at distinct frequencies which reduces partly or totally the energy at the specific frequency. With a detector these absorbed frequencies are identified (Vandenbergh., 2011) and a spectrum of the absorbance in function of the wavelength is obtained.

This technique permits to follow the binder oxidation with ageing, based on oxidation peaks observed in IR spectrometry, that is, the peaks at 1700 and 1030 cm-1 (Mouillet et al., 2010). The first peak is characteristic of the presence of carbonyl functions in the binder, while the second characterizes sulfoxide functions. Both are indicators of binder ageing, as they reflect the degree of oxidation. These chemical indicators are determined with an infrared spectrometer (Perkin Elmer Spectrum One) (Piérard and Vanelstraete, 2009). The binders are dissolved to a concentration of 75 g of binder/l of CCl4. Each spectrum is normalized as follows: correction of the baseline between 1885 and 459 cm−1 and absorbance coefficient of a standard bitumen peak situated between 1400 and 1500 cm−1 brought to 1.2.

To evaluate the oxidation degree, the following surface area peaks have been studied:

A1700 (area comprised between 1530 and 1770 cm−1) indicating the presence of carbonyl functions (ketones. esters. carboxylic acids);

A1030 (area comprised between 1000 and 1105 cm−1) indicating the presence of sulfoxides compounds.

Atot summing all modifications recorded between 946 and 1885 cm−1.

Polymer content: it is determined by Fourier Transform Spectrometry according to the same experimental protocol than the one of oxidation degree. The only difference is that to evaluate the relative polymer content, it has been necessary to measure the height of the following peaks:

H700: peak height at 700 cm-1 indicating the presence of styrene.

H968: peak height at 968 cm-1 indicating the presence of butadiene.



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Force ductility and elastic recovery: force ductility tests were conducted according to EN 13589 at a temperature of 25°C. According to EN 13703 the force ductility tests were evaluated to obtain following results:

Maximum Force FMax.

Deformation energy up to a deflection of 200 mm E0.2 [J].

Deformation energy between deflection of 200 and 400 mm E0.2-0.4 [J].

Further. the values of elastic recovery RE [%] according to EN 13398 were measured.

Complex modulus: all tests were undertaken using a HAAKE MARS II controlled stress rheometer featuring an accurate temperature controlled water bath. The hot recovered binder was poured into an aluminium mould and allowed to cool down and stay for 24 hours at room temperature prior to testing. After cooling, the sample was trimmed using a hot blade and removed from the aluminium mould. As this aluminium mould has exactly the same dimensions as the testing configuration, the disk of bituminous binder was directly placed on the upper plate of the dynamic shear rheometer. A thermal equilibrium time of 15 minutes was used at each testing temperature (25 and 52°C) before measuring complex modulus and phase angle at two different frequencies: 1.6 and 10 Hz. Two different geometries were used as a function of the binder stiffness: 8 mm and 25 mm parallel plates were used respectively for the tests performed at 25°C and 52°C. All of the measurements were conducted under stress-controlled mode and the applied stress was kept within the linear viscoelastic range. Three repeatability trials have been done at each temperature and frequency.

Prior to the analysis, the reheating and re-homogenisation of recovered binders was done at a maximum temperature of 160°C with a certain duration that each lab had chosen and noted. The duration of reheating depended on the size of sample. Then, before performing all the characterization methods, the Fourier Transform InfraRed (FTIR) spectroscopy was used to detect the presence of impurities in the recovered binder. Indeed, the presence of solvent residues or of other contaminants (grease, …) in the recovered binder can induce differences in the characteristics (penetration, softening point, etc.) of the recovered binder. For example, a residue of solvent such as toluene induces a lower softening point value and a higher penetration value. So, the FTIR spectroscopy method on recovered binder was used to detect the presence of such impurities. It will be shown up in the spectrum by the presence of new or larger peaks. The comparison of the obtained spectra for each recovered binder does not show any contaminants except in the serie of the MR-RA1 where two binders are contaminated (see Figure 3).



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Figure 3: FTIR spectra of MR- RA1 recovered binders dissolved in CCl4.

The contaminated MR- RA1 binders are from IBDIM and BRRC (Tol). On the spectra, we observed:

For IBDiM PCE binder, particularly the presence of extra peak at 1730 cm-1 and between 1250 and 1315 cm-1.

For BRRC Tol binder, the presence of toluene (new peak at 700 cm-1). These contaminations will caused some differences on the characteristics of these recovered binder and can be not attributed to an impact of the chosen recovery method. So we have decided to discuss the infrared spectroscopy results (polymer content and oxidation degree), the softening point and the complex modulus without taking account the characteristics measured on this two binders by adding a column called “MR-RA1 corr”.

It has to be noted that due to the low amount of binders recovered from MR-OAO and MR-RA1 mixes, there were not enough quantities for all the tests. Consequently, it was decided to perform only one test per category : Ring and Ball test for the assessment of consistency, complex modulus for rheological approach and infrared spectroscopy for chemical analysis.



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3.3.2 Results of penetration measurements

The results of penetration tests are summarized in Table 8 and Table 9. With spans of the values measured of 7 and 8 1/10 mm the scattering found on aged and unaged AC 11 samples is considerably larger than repeatability and reproducibility defined in EN 1426, where r = 2 1/10 mm and R = 3 1/10 mm.

Recovered binders from :

BRRC (1) BRRC (2) BRRC (3) IBDiM LR Aix TUBS (1) TUBS (2) ZAG

Solvent TCE Tol DCM PCE DCM TCE Tol TCE

Extraction method

Automatic extractor

Bottle Bottle Hot

extractor Dissolution

at 30°C Automatic extractor

Hot extractor

Automatic extractor

Binder separation Automatic centrifuge

CFC CFC CFC Bucket

centrifuge type 2

Automatic centrifuge

CFC Automatic centrifuge

AC11 unaged

Pen [1/10 mm] 29 30 32 30 33 26 -* -*

AC11 aged

Pen [1/10 mm] 16 23 17 15 18 16 16 -*

*Not enough sample material - No sample

Table 8 : Penetration at 25°C (1/10 mm) of the recovered binder

Penetration [1/10 mm] AC11 unaged AC11 aged

Mean (m) 30 17.5 Standard Deviation (sd) 2.45 2.88

Variation Coefficient (sd/m) 8.2% 16.5% Maximum 33 23 Minimum 26 15

Span 7 8

Table 9 : Main results of the penetration at 25°C measured for each material

In Figure 4 the deviation of each AC11 samples penetration is compared to the overall mean. It can be observed, that by application of extraction methods using warm or hot solvent (hot extraction and automatic extraction device as used in BRRC(1), TUBS(1), IBDiM, TUBS(2)), the penetration tends to lower values compared to extraction methods using cold solvent (cold mix dissolution and bottle rotating method (LRAix, BRRC(2), BRRC(3)). To check this observation, the mean penetration values measured of the samples coming from the same extraction



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procedure regarding temperature were calculated and are shown in Figure 5 together with error bars indicating the range of measured values. To add additional values, the results already presented in deliverable D1.2 were added to this analysis. In all cases but except for the RA sample containing physically linked SBS cold extraction results in the highest penetration results which may indicate less aging during extraction. For 3 samples (SMA+RA, AC11 unaged and AC11 aged) this difference can be considered as significant if the range of values are taken into account.

Figure 4: Deviation of penetration values of each binder samples from overall mean.

Figure 5: Mean Penetration for applied extraction methods (results of samples discussed in D1.2 added).



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3.3.3 Results of Ring & Ball temperature measurements

The results are summarized in Table 10 and are the average of two measurements (except for the mix AC11 in the case of LR-AIX unaged, IBDiM and BRRC TCE aged where only one measurement has been carried out).

It has to be noted that the normal rounding off of values from EN 1427 is not used (0.2 °C for TR&B ≤ 80 °C and 0.5 °C for TR&B > 80 °C) to better differentiate between the values of the round robin.


BRRC (1) BRRC (2) BRRC (3) IBDiM

IFSTTAR LR Aix TUBS (1) TUBS (2) ZAG

Solvent TCE Tol DCM PCE PCE DCM TCE Tol TCE

Extraction method Automatic extractor

Bottle Bottle Hot

extractor Hot



Hot extractor

Automatic extractor


CFC CFC CFC

CFC Bucket

centrifuge type 2



AC11 unaged

R&B1 56.0 56.2 55.9 56.0 56.3 55.6 58.4 59.1 --

AC11 aged

TR&B (°C) 66.3 65.9 65.6 66.4 65.0 65.8 66.4 65.6 --

MR-OAO

TR&B (°C) 64.0 61.6 63.2 63.8 -- 61.2 62.8 66.0 --

MR-RA1

TR&B (°C) 74.0 (69.2)* 74.0 (69.6)* -- 73.4 74.9 73.8 --

* FTIR measurements indicated the existence of solvent or other pollutant in the sample -- No sample

Table 10 : Softening point values of the recovered PmB for each material tested



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TR&B (°C] AC11 unaged AC11 aged MR-OAO MR-RA1 MR-RA1 corr

Mean (m) 56.7 63.2 63.2 72.7 74.0

Standard Deviation (sd) 1.3 1.6 1.6 2.3 0.6

Variation Coefficient (sd/m) 2.30% 2.55% 2.52% 3.18% 0.74%

Minimum 55.6 61.2 61.2 69.2 73.4

Maximum 59.1 66.0 66.0 74.9 74.9

Span 3.5 4.8 4.8 5.7 1.5

Table 11 : Main results of the softening point measured for each material

The Table 10 and Fel! Hittar inte referenskälla. show that:

In the case of the AC11 mixes (aged and unaged). the impact of the recovery method seems to be:

o limited on the unaged mix: the softening point values are scattered but the spans are comparable to the reproducibility value of the EN 1427 (R=3.5°C);

o important on the aged mix: the aging of the AC11 mix increases the softening point of around 7°C and the span from 3.5 to 4.8 (this value exceeds the reproducibility value).

o In tendency. the aging effect hot and warm extraction can be observed compared to cold extraction methods, for which TR&B temperature is slightly lower.

In the case of MR mix (MR-OAO (unaged) or MR-RA1 (aged)).

o the values of the softening point are more scattered and the spans exceed the reproducibility value, particularly in the case of MR-RA1. For latter material. the larger span can be explained by the presence of contaminant (see point 3.3.1). The exclusion of these two results decreases the span to 1.5 (MA-RA1 corr).

o The aging of MR mix increases also the softening point of around 10°C. If the results for the contaminated binder are not taken into account, the aging of MR mix decreases the span below the reproducibility value.

The deviation of each measured ring & ball temperature from the overall mean value is shown in Figure 6. The effect of extraction method (temperature) is analyzed in Figure 7 showing the mean values calculated for each recovery method. To help the evaluation, the results obtained in D1.2 are added to this figure. The tendency observed for penetration can also be observed for ring & ball temperature. Cold extraction leads to comparably low Ring&Ball temperatures which indicates less aging for these samples.



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Figure 6: Deviation of ring & ball softening temperature values of each binder samples from overall mean.



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Figure 7: Mean ring & ball temperature for applied extraction methods (results of samples discussed in D1.2 added).

3.3.4 Results of oxidation degree

The aging level of the binder in the reclaimed asphalt often is the predominant parameter determining the possibility to reuse the material in new hot asphalt mixes or to recycle it with less added-value as unbound material in the road base. Currently, this aging level is determined by Fourier Transform InfraRed spectrometry, which permits to follow the binder oxidation in ageing, based on oxidation peaks observed in IR spectrometry, that is, the peaks at 1700 and 1030 cm-1 (Mouillet et al.. 2010). The first peak is characteristic of the presence of carbonyl functions in the binder, while the second characterizes sulfoxide functions. Both are indicators of binder ageing, as they reflect the degree of oxidation.

The preparation of the binder and the normalization of the spectrum are described in the section 3.3.1 To evaluate the oxidation degree, the following surface area peaks investigated were (see Table 12):

A1700 (area comprised between 1530 and 1770 cm−1) indicating the presence of carbonyl functions (ketones, esters, carboxylic acids);

A1030 (area comprised between 1000 and 1105 cm−1) indicating the presence of sulfoxides;

Atot summing all modifications recorded between 946 and 1885 cm−1.


BRRC (1) BRRC (2) BRRC (3) IBDiM IFSTTAR LR Aix TUBS (1) TUBS (2) ZAG

Solvent TCE Tol DCM PCE PCE DCM TCE TolL TCE

Extraction method

Automatic extractor

Bottle Bottle Hot

extractor Hot



Hot extractor

Automatic extractor


CFC CFC CFC CFC Bucket

centrifuge type 2



AC 11 unaged

A1700 11.2 11.9 11.7 11.6 12.6 11.1 13.1 13.0 --

A1030 5.7 5.7 6.0 5.8 5.3 5.2 6.7 6.3 --

Atot 155.9 155.7 156.7 156.1 157.0 154.1 160.9 159.5 --

AC11 aged

A1700 15.9 15.2 15.8 16.1 16.3 16.0 16.0 -- --

A1030 7.0 6.6 7.1 6.9 6.7 6.5 7.6 -- --

Atot 172.4 169.5 171.5 173.1 173.8 172.1 171.2 -- --



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MR-OAO

A1700 10.7 10.4 10.8 10.1 -- 11.1 11.6 11.8 --

A1030 4.9 4.8 5.0 4.9 -- 5.0 5.1 5.4 --

Atot 157.2 153.3 155.1 153.5 -- 155.9 157.6 158.9 --

MR-RA1

A1700 14.9 14.4 14.1 17.2 -- 14.6 15.1 14.9 --

A1030 6.8 6.3 6.4 7.0 -- 6.2 6.5 6.6 --

Atot 175.9 167.6 168.7 180.5 -- 170.6 170.6 171.4 --

Table 12 : Oxidation characteristics of the recovered PmB for each material tested

(-- No sample)

The following values can be retained from all these trials:

Carbonyl functions (A1700) AC11 unaged AC11 aged MR-OAO MR-RA1 MR-RA1corr

Mean (m) 12.0 15.9 10.9 15.0 14.7



Minimum 11.1 15.2 10.1 14.1 14.1

Maximum 13.1 16.3 11.8 17.2 15.1

Span 2.0 1.1 1.7 3.1 1.0

Table 13 : Main results of the carbonyl content measured for each material

Sulfoxide functions (A1030) AC11 unaged AC11 aged MR-OAO MR-RA1 MR-RA1corr

Mean (m) 5.8 6.9 5.0 6.5 6.5



Minimum 5.2 6.5 4.8 6.2 6.2

Maximum 6.7 7.6 5.4 7.0 6.8 Span 1.5 1.1 0.6 0.8 0.6

Table 14 : Main results of the sulfoxide content measured for each material

Oxidation state (Atot) AC11 unaged AC11 aged MR-OAO MR-RA1 MR-RA1corr

Mean (m) 157.0 171.9 155.9 172.2 171.4





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Minimum 154.1 169.5 153.3 167.6 168.7

Maximum 160.9 173.8 158.9 180.5 175.9

Span 6.8 4.3 5.6 12.9 7.2

Table 15 : Main results of the oxidation state measured for each material

The Table 13 and Table 14 show that the two aged mixes (AC11 aged and MR-RA1) exhibit a content of carbonyl and sulfoxides functions higher compared to new mix caused by ageing occurring during the RILEM aging protocol. The increase due to aging protocol is similar for the two types of materials.

The coefficient of variation of the carbonyl content is not very influenced by the type of mix but is lower if the recovered binder has been aged. It can be explained by the different delays between fabrication of the mix and the recovery. As the binder aging occurs more quickly when the sample is not aged, the aging state between the different unaged samples can be more important and could explain the larger span of unaged samples compared to aged samples.

The coefficient of variation of the sulfoxide content is not really influenced by the type of mix or by its aging state.

The coefficient of variation of global oxidation state (see Table 15) is not influenced by the type of mix but changes when each mix is aged. The decrease of this coefficient after aging of AC11 mix is explained in the same manner than for the carbonyl content. However, no explanation could be given for the low increase of the variation coefficient after aging of MR mix.

3.3.5 Results of polymer content

The Fourier Transform InfraRed (FTIR) spectroscopy can also be used to locate the infrared absorption bands characteristics of SBS copolymers (Farcas et al., 2009), in order to identify an impact of the extraction procedure on the relative polymer content of recovered binders.

The preparation of the binder and the normalization of the spectrum are described in the section 3.3.1 To evaluate the relative polymer content, the height of the following peaks were measured (see Table 16):

H700: peak height at 700 cm-1 indicating the presence of styrene,

H968: peak height at 968 cm-1 indicating the presence of butadiene.



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Solvent TCE Tol DCM PCE PCE DCM TCE TolL TCE

Extraction method

Automatic extractor

Bottle Bottle Hot

extractor Hot



Hot extractor

Automatic extractor



centrifuge type 2



AC 11 unaged

H700 0.000 0.000 0.000 0.000 0.000 0.000 -0,001 0,000 --

H968 0.026 0.020 0.024 0.019 0.021 0.027 0,022 -0,019 --

AC11 aged

H700 0.000 0.000 0.000 0.000 0.000 0.000 0,001 -- --

H968 0.023 0.025 0.018 0.026 0.026 0.020 0,020 -- --

MR-OAO

H700 0.000 0.002 0.001 0.000 -- 0.001 0.000 0.001 --

H968 0.066 0.067 0.060 0.060 -- 0.067 0.062 0.062 --

MR-RA1

H700 0.000 0.005 0.001 0.004 -- 0.001 0.001 0.001 --

H968 0.060 0.060 0.061 0.062 -- 0.065 0.055 0.061 --

Table 16 : Intensity of polymer peak of the recovered PmB for each material tested

(-- No sample)


Styrene presence (H700) AC11 unaged AC11 aged MR-OAO MR-RA1 MR-RA1 corr

Mean (m) 0.000 0.000 0.001 0.002 0.001 Standard Deviation (sd) 0.000 0.000 0.001 0.002 0.000

Variation Coefficient (sd/m) -282.84% 282,84% 105.83% 100.39% 55.90% Minimum -0.001 0.000 0.000 0.000 0.000 Maximum 0.000 0.001 0.002 0.005 0.001

Span 0.001 0.001 0.002 0.005 0.001

Table 17 : Main results of the stryrene presence measured for each material



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Butadiene presence (H968) AC11 unaged AC11 aged MR-OAO MR-RA1 MR-RA1 corr

Mean (m) 0.022 0.023 0.063 0.061 0.060 Standard Deviation (sd) 0.003 0.003 0.003 0.003 0.004

Variation Coefficient (sd/m) 13.96% 14.55% 4.97% 4.94% 5.92% Maximum 0.019 0.018 0.060 0.055 0.055 Minimum 0.027 0.026 0.067 0.065 0.065

Span 0.008 0.008 0.007 0.010 0.010

Table 18 : Main results of the butadiene presence measured for each material

The results show that there is no SBS in the recovered binder of AC11 and MR mixes (aged and unaged).

This is conforming to our expectation for the mix AC 11 but not for the mix MR. In this latest case, the binder used to produce the mix is announced as modified with SBS. The small intensity of the butadiene peak can be due to the binder and cannot be attributed to SBS for which the styrene peak must also be present.

3.3.6 Results of complex modulus and phase angle

The results are shown in Table 19.



Solvent TCE Tol DCM PCE PCE DCM TCE Tol TCE


Bottle Bottle Hot

extractor Hot



Hot extractor

Automatic extractor



centrifuge type 2



AC 11 unaged

G* (Pa) and (°) at 25°C and 1.6 Hz

4.19 106 ( = 57.2)

4.50 106 ( = 57.7)

4.35 106 ( = 58.3)

4.19 106 ( = 57.5)

/

/

4.06 106 ( = 58.9)

7.18 106 ( = 51.9)

-- --

G* (Pa) and (°) at 25°C and 10 Hz

1.25 107 ( = 48.3)

1.35 107 ( = 48.7)

1.33 107 ( = 48.7)

1.25 107 ( = 48.5)

/

/

1.25 107 ( = 49.9)

1.94 107 ( = 43.3)

-- --


2.77 104 ( = 81.2)

2.79 104 ( = 81.2)

2.97 104 ( = 81.7)

3.06 104 ( = 81.4)

/

/

3.08 104 ( = 81.6)

5.39 104 ( = 78.3) -- --


1.43 105 ( = 75.4)

1.45 105 ( = 75.4)

1.53 105 ( = 75.7)

1.58 105 ( = 75.3)

/

/

1.59 105 ( = 75.5)

2.60 105 ( = 70.4) -- --



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AC11 aged


1.15 107 ( = 42.5)

1.19 107 ( = 42.8)

1.18 107 ( = 43.5)

1.20 107 ( = 42.3)

/

/

1.15 107 ( = 43.1)

1.31 107 ( = 41.4)

-- --


2.62 107 ( = 35.8)

2.72 107 ( = 35.9)

2.70 107 ( = 36.4)

2.74 107 ( = 35.5)

/

/

2.67 107 ( = 36.2)

2.91 107 ( = 34.9)

-- --


1.55 105 ( = 69.0)

1.43 105 ( = 69.1)

1.42 105 ( = 70.3)

1.50 105 ( = 68.7)

/

/

1.55 105 ( = 69.2)

1.56 105 ( = 67.7) -- --


6.12 105 ( = 57.2)

5.58 105 ( = 58.3)

5.79 105 ( = 59.1)

6.09 105 ( = 57.4)

/

/

6.31 105 = 57.7)

6.05 105 ( = 56.3) -- --

MR-OAO


1.87 106 ( = 51.1)

1.64 106 ( = 53.6)

2.05 106 ( = 52.0)

1.67 106 ( = 52.5)

/

/

1.44 106 ( = 55.0)

2.65 106 ( = 48.0)

2.41 106 ( = 49.3) --


5.24 106 ( = 47.0)

4.77 106 ( = 48.9)

5.75 106 ( = 47.1)

4.76 106 ( = 48.1)

/

/

4.34 106 ( = 50.3)

6.93 106 ( = 43.6)

6.40 106 ( = 45.0) --


2.88 104 ( = 63.6)

2.41 104 ( = 66.8)

3.42 104 ( = 65.7)

2.86 104 ( = 65.0)

/

/

2.57 104 ( = 67.3)

4.89 104 ( = 61.8)

4.23 104 ( = 62.8) --


1.09 105 ( = 61.3)

9.64 104 ( = 64.4)

1.33 105 ( = 62.8)

1.09 105 ( = 63.2)

/

/

1.04 105 ( = 64.8)

1.76 105 ( = 58.5)

1.53 105 ( = 59.8) --

MR-RA1


4.89 106 ( = 39.8)

2.61 106 ( = 44.7)

5.70 106 ( = 40.7)

3.00 106 ( = 44.0)

/

/

5.00 106 ( = 41.8)

5.36 106 ( = 39.2)

5.57 106 ( = 39.8) --


1.09 107 ( = 36.2)

6.64 106 ( = 40.5)

1.28 107 ( = 36.7)

7.16 106 ( = 40.2)

/

/

1.16 107 ( = 37.8)

1.15 107 ( = 35.4)

1.22 107 ( = 36.0) --


1.33 105 ( = 54.7)

6.31 104 ( = 59.2)

1.30 105 ( = 56.6)

7.91 104 ( = 57.5)

/

/

1.23 105 ( = 57.2)

1.16 105 ( = 55.4)

1.29 105 ( = 55.8) --


4.08 105 ( = 49.3)

2.13 105 ( = 55.4)

4.19 105 ( = 50.9)

2.56 105 ( = 53.5)

/

/

3.90 105 ( = 51.6)

3.61 105 ( = 50.0)

4.05 105 ( = 50.0) --

-- No sample

Table 19 : Rheological characteristics of the recovered PmB for each material tested




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Rheological parameters AC11 unaged AC11 aged

25°C and 1.6 Hz G*(Pa) G*(Pa)

Mean (m) 4.75 106 56.9 1.20 107 42.6

Standard Deviation (sd) 1.20 106 2.53 0.06 107 0.73

Variation Coefficient (sd/m) 25.3% 4.4% 4.9% 1.7%

Maximum 7.18 106 58.9 1.31 107 43.5

Minimum 4.06 106 51.9 1.15 107 41.4

Span 3.12 106 7.0 0.16 107 2.1

25°C and 10 Hz G*(Pa) G*(Pa)

Mean (m) 1.40 107 47.9 2.73 107 35.8



Maximum 1.94 107 49.9 2.91 107 36.4

Minimum 1.25 107 43.3 2.62 107 34.9

Span 0.69 107 6.6 0.29 107 1.5

52°C and 1.6 Hz G*(Pa) G*(Pa)

Mean (m) 3.34 104 80.9 1.50 105 69.0



Maximum 5.39 104 81.7 1.56 105 70.3

Minimum 2.77 104 78.3 1.42 105 67.7

Span 2.62 104 3.4 0.14 105 2.6

52°C and 10 Hz G*(Pa) G*(Pa)

Mean (m) 1.70 105 74.6 5.99 105 57.7



Maximum 2.60 105 75.7 6.31 105 59.1

Minimum 1.43 105 70.4 5.58 105 56.3

Span 1.17 105 5.3 0.73 105 2.8

Table 20 : Main results of the rheological parameters measured for AC11 mix



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Rheological parameters MR-OAO unaged MR-RA1 aged MR-RA1 aged corr

25°C and 1.6 Hz G*(Pa) G*(Pa) G*(Pa)

Mean (m) 1.96 106 51.6 4.59 106 41.4 5.30 106 40.3

Standard Deviation (sd) 0.438 106 2.42 1.258 106 2.17 0.352 106 1.01

Variation Coefficient (sd/m) 22.3% 4.7% 27.4% 5.2% 6.6% 2.5%

Maximum 2.65 106 55.0 5.70 106 44.7 5.70 106 41.8

Minimum 1.44 106 48.0 3.00 106 39.2 4.89 106 39.2

Span 1.21 106 7.0 2.70 106 5.5 0.81 106 2.6

25°C and 10 Hz G*(Pa) G*(Pa) G*(Pa)

Mean (m) 5.46 106 47.1 1.04 107 37.5 1.18 107 36.4



Maximum 6.93 106 50.3 1.28 107 40.5 1.28 107 37.8

Minimum 4.34 106 43.6 0.66 107 35.4 1.09 107 35.4

Span 2.59 106 6.7 0.62 107 5.1 0.19 107 2.4

52°C and 1.6 Hz G*(Pa) G*(Pa) G*(Pa)

Mean (m) 3.32 104 64.7 1.10 105 56.6 1.26 105 55.9



Maximum 4.89 104 66.8 1.33 105 59.2 1.33 105 57.2

Minimum 2.41 104 61.8 0.63 105 54.7 1.16 105 54.7

Span 2.48 104 5.0 0.70 105 4.5 0.17 105 2.5

52°C and 10 Hz G*(Pa) G*(Pa) G*(Pa)

Mean (m) 1.26 105 62.1 3.50 105 51.5 3.97 105 50.4



Maximum 1.76 105 64.8 4.19 105 55.4 4.19 105 51.6

Minimum 0.96 105 58.5 2.13 105 49.3 3.61 105 49.3

Span 0.80 105 6.3 2.06 105 6.1 0.58 105 2.3

Table 21 : Main results of the rheological parameters measured for MR mix

The Table 20 and Table 21 show that the G* of two artificial RA are higher than the ones before laboratory aging and the lower, whatever the temperature and



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frequency. It is in good agreement with the results of oxygeneated compounds and consistency tests.

The coefficient of variations and spans are quite important for G* measured on the new mixes (before RILEM aging). Compared to the relative standard deviations obtained in the frame of the RILEM round robin test (15% to 30% for G*) (Vanelstraete et al., 2008) and the round robin test perfomed by GE1 French working group (10% to 30% for G*) (Eckmann et al., 2008), they are of the same magnitude that means the impact of method used for the extraction and recovery process is weak in comparison to the reproducibilty of the analysis. However, it has to be noted that after RILEM aging the two artificial RA (AC11 aged and MR-RA1 aged corr) exhibit lower coefficient of variations (around 3-6%) and spans. It could be explained by the different impact on the aging stage of the binder due to different delays between preparation (manufacturing with or without laboratory aging) of the mix and the recovery process of the binder. As the binder aging occurs more quickly when the sample is not aged, the aging state between the different unaged samples can be more important and could explain the larger span of unaged samples compared to aged samples.

For the angle phase, previous rond robin tests (Vanelstraete et al., 2008; Eckmann et al., 2008) found standard deviations values lower than 10%, mostly lower to 5%. This has also been the case in this round robin test in which the lowest standard deviation has been obtained for the aged binders (around 2%).

Concerning the solvent used, it can have an impact on the rheological parameters as seen on the binders recovered from the same extraction procedure of BRRC using either toluene or dichloromethane: the chlorinated solvent gives the lowest phase angle value and the highest norm of complex modulus, in the case of MR-OAO. One may suspect dichloromethane to lead to a more elastic recovered binder.

To conclude. the variations observed remain within the known reproducibility limits for the rheological analysis using a controlled stress rheometer, underlining the problem on how to best handle such aged binders products in the frame of rheological measurement.

3.3.7 Results of ductility force and elastic recovery

Force ductility tests were conducted according EN 13589 at a temperature of 25°C. The results measured on the binder samples extracted from the AC11 unaged and aged samples are plotted in Figure 8.

According EN 13703 the force ductility tests were evaluated to obtain following results:

Maximum Force FMax.

Deformation energy up to a deflection of 200 mm E0,2 [J/cm²],

Deformation energy between deflection of 200 and 400 mm E0,2-0,4 [J/cm²].



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The results are summarised in table 22.

Table 23 contains the mean values and indicators of scattering for the maximum force FMax measured in the tests, whereas the relative difference of each FMax value to the overall mean is plotted in Figure 8.

Figure 8: Course of ductility force versus ductility (left: AC unaged, right: AC aged).


BRRC (1) BRRC (2) BRRC (3) IBDiM LR Aix TUBS (1) TUBS (2) ZAG

Solvent TCE Tol DCM PCE DCM TCE Tol TCE


Bottle Bottle Hot



Hot extractor

Automatic extractor


CFC CFC CFC Bucket

centrifuge type 2



AC11 unaged

FMax [N]

E0,2 [J/cm²]

E0,2-0,4 [J/cm²]

6.7

0.433

0.053

5.9

0.374

0.045

5.6

0.354

0.042

5.8

0.368

0.045

4.4

0.278

0.031

7.6

0.512

0.055

6.7

0.461

0.051

--

--

--

AC11 aged

FMax [N]

E0,2 [J/cm²]

E0,2-0,4 [J/cm²]

34.2

2.408

0.107

30.6

2.205

0.178

28.8

2.124

0.223

30.0

2.172

0.192

27.5

2.007

0.108

32.3

2.343

0.113

24.4

1.555

0.033

--

--

--

-- No sample

Table 22 : Results of force ductility an elastic recovery tests.



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FMax[N] AC 11 unaged AC 11 aged

Mean (m) 6.1 29.7 Standard Deviation (sd) 1.0 3.3

Variation Coefficient (sd/m) 16.7 % 10.9 % Maximum 7.6 34.4 Minimum 4.4 24.4

Span 3.2 10

Table 23 : Main results of the maximum force FMax, obtained from force ductility tests.

Figure 9: Deviation of the measured maximum force FMax from the mean values.

Table 24 contains the mean value as well as scattering indicators for the deformation energy measured up to a ductility of 200 mm. The scatter (variation coefficient) for the fresh asphalt mix is higher compared to the scatter measured on the artificially aged RA. Reason for this is the higher absolute value of deformation energy obtained which balances the increase standard deviation and span between minimum and maximum value measured.



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E0.2 [J/cm²] AC 11 unaged AC 11 aged

Mean (m) 0.397 2.116 Standard Deviation (sd) 0.078 0.281

Variation Coefficient (sd/m) 19.5 % 13.3 % Maximum 0.512 2.408 Minimum 0.278 1.556

Span 0.234 0.852

Table 24 : Main results of the deformation energy obtained between 0 and 200 mm ductility E0,2, obtained from force ductility tests.

3.3.8 Choice of relevant indicators for recyclability potential’s assessment

The exploitation of round robin test on characteristics of recovered binders has underlined that it is necessary to perform the infrared spectroscopy analysis before performing all others characterization methods for two reasons:

Identification of recovered binders contaminated by residual solvent that can cause some differences on the characteristics,

Determination of the type of bituminous binders (pure or modified) in RA in order to take into account the presence or not of polymers for the choice of adding binder in recycling process. This is a key point for the recycling of components with high quality (e.g. high quality aggregates, modified binders). For example, in this study, the binder used to produce the MR-OAO unaged and MR-RA1 aged mixes was announced as modified with SBS. However, the analysis by Fourier Transform InfraRed spectroscopy has shown only a small intensity of the butadiene peak that can be due to the binder and cannot be attributed to SBS for which the styrene peak must also be present. It has to be noted that the presence of polymers cannot be assessed by consistency tests, so the infrared spectroscopy is a very promising tool for this issue.

Then in order to select the most relevant indicators for estimating the recycling potential of a RA, it is necessary to characterize and to know the ageing and end of life (binder state) of binders. It is the reason why we have produced in laboratory artificial RA with exactly known binder properties. The evolution of their characteristics after laboratory ageing have been compared with the ones determined on Stone Mastic Asphalt (called “SMA8”) with modified bitumen as virgin binder and including 15% of RA (also with PmB; source not known) and 2 actual RA of age 10 years (see deliverable D1.2) : a French Porous Reclaimed Asphalt (called “PRA”) including a physical SBS modified bitumen and a Reclaimed Asphalt (called “RA(V1)”) with a chemically linked SBS modified bitumen (Styrelf) (seeTable 25).



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Characteristics (*) AC11 aged MR-RA1 aged

(corr) SMA8 PRA RA(V1)

Softening Point (°C) 65.9 74.0 71.2 72.6 82.5

Increase of softening point (°C) 9.7 10.8 / / /

Content of carbonyls 15.9 14.7 14.8 21.5 21..8

Increase of content of carbonyles 4.2 3.8 / / /

Content of sulfoxydes 6.8 6.5 6.4 7.5 6..9

Increase of content of sulfoxydes 1.2 1.4 / / /

G* at 25°C and 1.6 Hz 1.20 107 5.30 106 7.53 106 2.31 107 2.33 107

Increase of G* at 25°C and 10 Hz 0.73 107 3.34 106 / / /

at 25°C and 1.6 Hz 42.6 40.3 44.7 36.7 40.0

Decrease of at 25°C and 1.6 Hz 14.3 11.3 / / /

G* at 52°C and 1.6 Hz 1.50 105 1.26 105 1.53 105 3.80 105 3.96 105

Increase of G* at 25°C and 10 Hz 1.17 105 0.93 105 / / /

at 52°C and 1.6 Hz 69.0 55.9 61.9 61.3 56.7

Decrease of at 25°C and 1.6 Hz 11.9 8.8 / / /

Table 25 : Evolution of characteristics during artificial ageing and comparison with actual materials.

(* the results are expressed as the mean of the characteristics measured on the binders recovered from mixes by different laboratories using different methods and solvents as

authorized in EN 12697-1 and EN 12697-3).

For the two artificial RA, the increase of softening point, content of carbonyls and sulfoxides is of the same magnitude. However, the increase of complex modulus and decrease of phase angle at 25 and 52°C are more important for AC11 mix.

The characteristics that lead to differentiate the 2 actual RA (called PRA and RA (V1)) are the content of carbonyls (more important due to the oxidative ageing) and the complex modulus at 25 and 52°C, either 1.6 Hz or 10 Hz (higher due to the hardening of binder). It means that these two characteristics are relevant to assess the end of life (binder state) of binders and could be used for the choice of adding binder (as indicators for the recyclability potential of aged binder). However, in the future, it would be interesting to define the threshold values of these characteristics for recycling a RA. This can be done only by data base.



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4 Conclusions

In concordance with the conclusions of deliverable D1.2, it was decided to carry on with the validation step of extraction procedures. The aim of this study was to identify suitable experimental parameters (solvent, methods and temperature of dissolution) to improve the determination of soluble binder content of RA containing PmB and the recovery of PmB for further characterization.

Consequently, the proposed experimental strategy consisted in producing in laboratory artificial RA with exactly known binder content and binder properties and then applying the different recovery methods according to EN 12697-1 and EN 12697-3 standards. As these standards describe a large range of methods and solvents that can be chosen to carry out the tests, the different results have been compared to the “true” ones in order to evaluate the adequacy of the methods and solvents proposed in standards for the right characterization of RA with PmB.

This experimental campaign have been performed on two kinds of asphalt mixes: one “standard mix with unmodified binder“ as reference (called “AC11”) and one PmB modified mix with “standard” PmB (called “MR”) before and after laboratory ageing. The binder used to produce the unaged and aged MR mixes was announced as modified with SBS. As it was shown by infrared spectroscopy analyses, it was not the case. Therefore, to reach the objective, the conclusions will be drawn on all the analyses presented in this deliverable (RA prepared in laboratory) but also thanks to results obtained from RA taken on site (described in deliverable D1.2). In fact, in a first step, a round robin test on soluble binder content has been performed and the obtained values have been compared to the ones of the three different bituminous materials evaluated in deliverable D1.2 (see Table 26): one Stone Mastic Asphalt including 15% of RA (called “SMA8”) and 2 others RA with physical (called “PRA”) and cross-linked elastomer (called “RA(V1)”) modified bitumens.

AC11 unaged

AC11 aged

MR-OAO unaged

MR–RA1 aged

SMA8 PRA RA(V1)

“True value” (mix design) 5.40% 5.40% 7.00% 7.00% / / /

Mean 5.49% 5.48% 6.78% 6.77% 6.85% 3.78% 6.42%

Standard Deviation 0.17% 0.24% 0.26% 0.17% 0.08% 0.40% 0.33%

Variation Coefficient 3.10% 4.38% 3.83% 2.51% 1.18% 6.33% 5.08%

Minimum 5.19% 5.05% 6.46% 6.49% 6.70% 3.40% 5.79%

Maximum 5.80% 5.92% 7.36% 7.04% 7.00% 4.23% 6.89%

Span 0.61% 0.87% 0.90% 0.55% 0.30% 0.83% 1.10%

Table 26 : Statistical analysis of soluble binder contents



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The results of the two actual RA with physical and cross-linked elastomer modified bitumens are very scattered around the mean value with the higher standard deviations and variation coefficients. Comparing to the results of others samples, the repeatability and the reproducibility are worse. Problems seem to appear for RA with PmB, for which the ageing level of the bitumen in the RA, combined with the presence of polymers leads to a more difficult recovery.

A key point underlined in this study is that it is very important to check that the residue on ignition (450°C during 8 hours) of the recovered binder has not to exceed 1% of the mass taken; otherwise, there is a bias on the soluble binder content that could be artificially higher.

The round robin tests sessions on artificial RA led to interesting results about the gap between the true value and the measurement that is more important for MR mixes than for AC11 mixes. It showed also the impact of the solvent on the tests results:

For AC11 mix aged, Toluene seems to be the best solvent.

For MR mix aged. Trichlorethylen seems to be better.

However, number of participating laboratories and repetitions was limited, so this result needs to be confirmed by a similar round robin test but at a larger scale: more participants, more repetitions and must be performed on RA with PmB of controlled quality (laboratory-aged).

In the meantime, the characteristics on recovered binders have been assessed. The analysis by Fourier Transform InfraRed spectroscopy has revealed that binders from MR mixes are not modified by SBS polymer as originally supposed. Consequently, the objective to select suitable experimental parameters among large range of methods and solvents proposed in European standards in order to obtain the correct binder content and the correct properties of PmB in RA could not be reached. But, comparing to the results of the 2 actual RA (called PRA and RA (V1)) described in deliverable D1.2, it is possible to determine the characteristics that are strongly related to the assessment of the end of life of RA, namely the physico-chemical state of the binder and its ageing level. They are:

the content of carbonyls (more important due to the oxidative ageing),

the complex modulus at 25 and 52°C (either 1.6 Hz or 10 Hz) (higher due to the hardening of binder).

It means that these two characteristics could be used for the choice of adding binder as indicators for the recyclability potential of aged binder. In the future, it would be interesting to define the threshold values of these characteristics for recycling a RA. This can be done only by collecting data.

To conclude. the European standards EN 12697-1 and EN 12697-3 appear not clear enough for Reclaimed Aspalts containing PmB. In the future, it seems very important to focus research on 2 key issues :



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firstly, characterization and technical evaluation of RA containing modified binders in order to assess their capability to be recycled, by mixing it with the fresh added bitumen in a new mix.

secondly, study of degradation process of the polymers in asphalt layers with modified bitumen in order to understand how to restore the polymeric modification during recycling.



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5 References

Choquet F. et al.. « The determination of SBS. EVA and APP polymers in modified bitumens ». Belg. ASTM Special technical publication. STP 1108. 1992. pp 35-49.

De la Roche C.. Van de Ven M.. Van den Bergh W.. Gabet T.. Dubois V.. Grenfell J. and Porot. L. (2009). “Development of a laboratory bituminous mixtures aging protocol”. Procs. Int. Conf. on Advanced Testing and Characterisation of Bituminous Materials. 2009.

De la Roche C.. Gabet T.. Van de Ven M.. Van den Bergh W.. Grenfell J. (2010). “Results of interlaboratory tests on a laboratory bituminous mixtures ageing protocol”. ISAP 2010. August 1 to 6. Nagoya. Japan.

Degeimbre R. et al.. « Dosage des polymères SBS et APP dans les bitumes modifiés ». Bituminfo. 1986. pp17-29.

Dumont A.G. et al.. « Study of the microstructure of modified binders by UV-Epifluorescence optical microscopy ». 1st Eurasphalt&Eurobitume Congress. Strasbourg 1996.

Farcas F.. Mouillet F.. Besson S.. Battaglia V.. Petiteau C.. Le Cunff F. “Identification et dosage par spectrométrie infrarouge à transformée de Fourier des copolymères SBS et EVA dans les liants bitumineux”. Testing method of LPC n°71 (2009). ME 71. ISSN 1167-489X. 9P.

Kluttz et al.. « Polymers in modified asphalt ». WRI Asphalt Additives Symposium. Laramie. USA. 2004.

Landa P. et al.. « De (on)mogelijkheid van terugwinning van PmB uit asfaltmengsels met behulp van dichloromethaan ». Werkbouwkundige Werkdagen. Doorwerth. juni 2006.

Lapalu L.. Planche J.P.. Mouillet V.. Dumas Ph.. Durrieu F.. ”Evolution of rheological properties of polymer-modified bitumens during their ageing”. Proceedings of Eurasphalt & Eurobitume Congress. Vienna (Austria). 12-14 Mai 2004. papier 210 (Session 5 “Ageing. durability and low temperature performance”). 8 p.

Molenaar J.M.M. et al.. « An investigation into the analysis of polymer modified bitumen (PmB) ». 3rd Eurasphalt & Eurobitume Congress. Vienna 2004.

Mouillet V.. Farcas F.. Battaglia V.. Besson S.. Petiteau C.. Lecunff F.. ”Identification and quantification of bituminous binder’s oxygenated species : Analysis by Fourier Transform InfraRed spectroscopy”. LPC Testing method n°69 (2010). ISSN 1167-489X. 9 p.

Nösler I.. Tanghe T.. Soenen H.. « Evaluation of binder recovery methods and the influence on the properties of polymer modified bitumen ». Eurasphalt and Eurobitume congress. Copenhague 2008.



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Piérard N.. Vanelstraete A.. ”Developing a test method for the accelerated ageing of bituminous mixtures in the laboratory”. Advanced Testing and Characterization of Bituminous Materials. Loizos. Partl. Scarpas & Al-Qadi. Taylor & Francis Group. London. 2009. 163-171.

Piérard N.. Vansteenkiste S.. Vanelstraete A.. « Effect of extraction and recovery procedure on the determination of PmB content and on the properties of the recovered binder ». Road materials and pavement design. EATA 2010. 251-279.

Piérard N.. Quid de l’extraction et de la récupération des liants modifiés au polymère d’enrobés bitumineux? Les procédures classiques sont-elles toujours applicables ?. Bulletin CRR. 3/11. 2011.p 12-16.

Piérard N.. Impact de l’extraction et de la récupération sur les propriétés des PmB faiblement modifiés. Workshop 6 sur les possibilités d’utilisation et de recyclage des enrobé bitumineux à base de bitume-polymère. Belgian Road Research Center. 18 Octobre 2012 .18 slides.

SETRA. Utilisation des normes enrobés à chaud (« User manuel of the hot asphalt mixtures standards »). Sétra (January 2008).

Van den bergh W.. The effect of ageing on fatigue and healing properties of bituminous mortars. Ph.D Thesis.Delft University of Technology. 14 december 2011.

Vanelstraete A.. Sybilsky D.. and co-authors from RILEM –TC PEB – TG1 « bituminous binders ». “Results of the RILEM Round Robin Test on Bituminous Binders Rheology”. 2nd Eurasphalt & Eurobitume Congress Barcelona 2000. Proc. 303.uk.

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Test Procedures/Methodologies for Reclaimed Asphalts Binder

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