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Publisher Copyright: © 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. The Multiple Stress Creep and Recovery test is recognised to better characterise the high-temperature property of bituminous binders than the traditional methods, especially for polymer modified bitumen (PmB). However, some experimental parameters may affect the test results, such as the preloading, measurement location, stress level. In this study, the effects of these parameters were evaluated through an interlaboratory experiment. Four bituminous binders were short-term aged and analysed by five different laboratories. The variability in most results met the requirements of the European standard, while some failed to pass the American precision criteria. The preloading at 0.1 kPa with ten cycles was found to have a recordable impact on PmB samples, but a less significant effect was observed for the unmodified ones. With the measurement locations, the influence is limited compared to other parameters. As for stress sensitivity, higher stresses lead to remarkable differences.

InfraRed spectrometry is a powerful technique to characterise bituminous binders. The methodology is not fully harmonised and may lead to vari-ability. The RILEM-272-PIM-TG1, evaluated seven complex bituminous, for which eleven laboratories performed FTIR. While, the spectra showed sim-ilar trends, further analysis was needed to improve comparison. A specific approach was applied on two binders, unmodified and polymer modified bitumen, and two ageing conditioning. Combining a Gaussian distributionand derivative analysis confirmed a good alignments of laboratory results. A two-step model was developed improving further interpretation. It con-sists of a baseline adjustment with eight points and normalisation over the maximum aliphatic peak. Furthermore, a specific fingerprint model was determined with the main absorption peaks defined by their location and shape. Only the intensity varies from laboratory to laboratory and binders. This general approach can be used as a platform to characterise aging or binder complexity

This article investigated the effect of waste polyethylene (PE) on the modified asphalt binders' rheological behavior from a statistical point of view. The interlaboratory testing results from the RILEM Technical Committee 279 Valorization of Waste and Secondary Materials for Roads Task Group 1 were used for this purpose. First, an unaged 70/100 penetration graded neat binder was selected as the reference material. Next, a single 5 % content of waste PE additives (PE-pellets and PE-shreds) was mixed with a 95 % neat binder to prepare two PE modified binders. Then, dynamic shear rheometer-based temperature-frequency sweep tests were performed over a wide range of temperatures and frequencies to evaluate the rheological properties of these three binders. Different rheological behaviors were observed in the isochronal plots at high temperatures. Based on a reproducibility precision requirement proposed for phase angle, 28 degrees C was set as the transition temperature across the rheological behaviors. Next, according to the three rheological behaviors defined in a previous study by the authors, statistical analysis was introduced to identify sensitive rheological parameters and determine the thresholds. Results indicate that the phase angle measured above 28 degrees C and 1.59 Hz can be used as a sensitive parameter to discriminate the three rheological behaviors of PE modified binders. The thresholds among different behaviors were also calculated as an example for phase angle measured at the highest common testing temperature of 70 degrees C. Additional experimental evaluations on more types of PE modified binders, especially at intermediate and high temperatures, are recommended to better understand their influence on the rheological behavior of PE modified binders.

Funding Information: The authors would like to acknowledge the contributions of the active members of the RILEM technical committee TC 264-RAP in terms of experimental results, data analysis and proofreading. The authors would also like to thank Nynas AB, Kraton Chemical BV and Technical University of Braunschweig for supporting the interlaboratory activity by providing bituminous materials, ARA and RA binder. Publisher Copyright: © 2022, The Author(s). This recommendation is based on the results of an inter-laboratory study organised by the RILEM technical committee TC 264-RAP "Asphalt Pavement Recycling"—Task Group 3 (TG3) focusing on Asphalt Binder for Recycled Asphalt Mixture. The TG3 aimed to evaluate the effect of a specific family of materials known as asphalt recycling agent (ARA) on the aged binder under different configurations. Even though ageing is an irreversible phenomenon, effective ARA must have the capability to improve the flexibility of the bituminous materials and their resistance against cracking susceptibility with no adverse effect on the rutting resistance of pavements containing reclaimed asphalt. A total of 17 participating laboratories analysed the properties of binder blends composed of aged binder from reclaimed asphalt in three different contents (60, 80, 100%), ARA and virgin binder. The physical properties of the blends were thoroughly evaluated through traditional and rheological binder testing. This recommendation proposes to restore the original material properties at low and intermediate temperatures (i.e. cracking resistance) while balancing the high-temperature characteristics (i.e. rutting susceptibility) with durable impact throughout the progression of ageing phenomena. Therefore, useing of the Dynamic Shear Rheometer is foreseen as a more suitable and sustainable means to evaluate binder blends containing an asphalt recycling agent. Compared with conventional testing, the proposed approach requires fewer materials while resulting in a faster experimental procedure with one single test.

inter-laboratory experiments were designed to evaluate the impact of plas- tic waste blended directly in bitumen and to assess the properties, using conventional and advanced bituminous binder testing. The blends tar- geted 5% of plastic waste in 95% bitumen, using two types of polyethy- lene (PE) primary (pellets) and secondary (shreds) waste. The experiments showed that the addition of PE waste to bitumen does not alter the chem- istry of the bitumen, the blending is physical. The DSR results indicate a strong dependency on the testing temperature as at low temperatures the composite material bitumen and PE behave both elastically whereas, at higher temperatures, the bitumen becomes viscoelastic. The MSCR tests indicated that the neat binder is more sensitive to permanent deformation compared to the blends with PE. The fatigue performance using the Linear Amplitude Sweep test showed a better performance in terms of stress and fatigue life for the PE blends.

Using bio-binder and bio-additives as recycling agents for asphalt mixtures with high-content of reclaimed asphalt (RA) is proving to be feasible. It is still not clear whether this combination might provide new hazardous emissions from airborne binder fumes. The health hazard related to airborne bitumen fume generation is primarily relevant for paving crews while there is little opportunity for exposure related to asphalt plant workers. In this study, measurements of gaseous organic compounds from airborne binder fumes of selected bio-asphalt mixtures have been measured during the laboratory mixing process, by using a thermo-mixer equipped with a chimney at University Gustave Eiffel. Parameters studied are the binder nature, mix formula and mixing temperatures. Results show that generally combining bio-based materials and RA is as safe as using conventional bitumen and RA, however thanks to this approach it was possible to identify a strong link between bituminous material composition and their emission potential

Funding Information: The RILEM Technical Committee on Valorisation of Waste and Secondary Materials for Roads (TC 279-WMR) and the members of Task Group 1 are gratefully acknowledged. The authors would also like to thank Nynas AB and Swiss company Innorecycling for supporting the interlaboratory activity by providing reference neat binder and PE-pellets, PE-shreds additives. The contribution of the Swiss National Science Foundation ( 205121_178991 ) to the Swiss partners is also acknowledged. Funding Information: The RILEM Technical Committee on Valorisation of Waste and Secondary Materials for Roads (TC 279-WMR) and the members of Task Group 1 are gratefully acknowledged. The authors would also like to thank Nynas AB and Swiss company Innorecycling for supporting the interlaboratory activity by providing reference neat binder and PE-pellets, PE-shreds additives. The contribution of the Swiss National Science Foundation (205121_178991) to the Swiss partners is also acknowledged. Publisher Copyright: © 2022 Significant volumes of waste materials such as plastics is generated every year worldwide with a potentially harmful impact on the environment. At the same time, the demand for asphalt modifiers has seen an increase over the year with consequent higher costs for these types of additives. Therefore, combining large amounts of available waste plastics with asphalt binder as an extender or modifier would potentially improve the paving material properties while limiting the disposed waste. While several rheological studies have been performed in the past, they were restricted to single research efforts hindering a consistent comparison among the valuable results of these investigations. For this reason, the Task Group 1 of the RILEM Technical Committee 279-WMR established a research activity with 11 international institutions to conduct interlaboratory research to evaluate the possibility of using waste polyethylene (PE) as an additive in asphalt binder. The study addressed the combined impact of PE materials andexperimental conditions on the rheological properties of asphalt binder. For this purpose, conventional tests (penetration value, softening point temperature, and Fraass breaking point temperature) and the linear viscoelastic characterization using the Dynamic Shear Rheometer (DSR) were adopted. An unaged pen grade 70/100 neat binder was selected as the reference binder; PE-pellets and PE-shreds, produced from the recycled waste polyethylene materials, were used as the polymer additives. A single content (5%) of PE-pellets and PE-shreds was used to blend the PE material with the reference binder (95%) and prepare the two PE modified binders. Results indicate that the use of plastic modifiers leads to an overall higher complex shear modulus and softening point temperature while decreasing the penetration value. Higher dispersion in the results, especially in phase angles, was observed for blended binders at high temperatures. The PE modified binders exhibited poor reproducibility among laboratories and a low level of repeatability. Such a scatter in the data could result from an uneven dispersion of plastic material at high temperatures. In contrast, plastic shapes and batches appeared to have a limited impact. Three different rheological behaviors, neat binder, modified binder, and complex modified binder, were visually identified among the interlaboratory results and based on a simple statistical analysis of variance. Further analysis of the data suggested that the Glover Rowe (G-R) parameter can be used as a sensitive tool to classify the rheological behaviors of PE modified binders. Further experimental evaluation on specific testing conditions, such as measurement gaps of DSR at high temperatures, is recommended to advance the understanding of their influence on the rheological behavior of PE modified binders.

Using bio-binder and bio-additives as recycling agents for asphalt mixtures with high-content of reclaimed asphalt (RA) is proving to be feasible. It is still not clear whether this combination might provide new hazardous emissions from airborne binder fumes. The health hazard related to airborne bitumen fume generation is primarily relevant for paving crews while there is little opportunity for exposure related to asphalt plant workers. In this study, measurements of gaseous organic compounds from airborne binder fumes of selected bio-asphalt mixtures have been measured during the laboratory mixing process, by using a thermo-mixer equipped with a chimney at Univ Gustave Eiffel. Parameters studied are the binder nature, mix formula and mixing temperatures. Results show that generally combining bio-binders and RA is as safe as using conventional bitumen and RA, however thanks to this approach it was possible to identify a strong link between bituminous material composition and their emission potential.

The asphalt industry is constantly working to enhance the performances of asphalt materials, introducing innovative and more sustainable solutions. In this context, the incorporation of materials, such as additives, polymers, is more and more used to improve the properties of neat bitumen. This leads to even more complex bituminous binders, raising the question, are the current specifications and test methods appropriate for complex materials? To deal with this, the RILEM Technical Committee 272-PIM 'Phase and Interphase behaviour of innovative bituminous Materials' with its Task Group TG1 is looking at the efficiency of various test methods for complex binders with an extensive inter-laboratory program with 17 laboratories. It includes seven different binders, two neat bitumen, two polymer modified bitumen and three binders with liquid additives, emphasising on compositional and physical changes at different conditions. The focus is low temperature; while a complementary experimental program encompasses as well as testing at intermediate and high temperatures. The outcomes of the work will provide indications on how robust the current binder characterisation techniques are and establish technical recommendations for future test methods specially designed for complex binders. Some first results are presented hereby.

The use of Dynamic Shear Rheometer (DSR) has become a standard tool to characterise bituminous binders, either for research or specifications purposes. Testing with the DSR enables to cover a wide range of temperature and frequency conditions in a fast way by using limited amount of materials. Depending of the test type, DSR measurements provide different rheological parameters to characterise physically the materials either at low, intermediate or high temperatures. At the same time, different test protocols have emerged. While the preferred mode is running in frequency sweep at different temperatures, the test can also be run with a temperature ramping at a fixed frequency. In order to evaluate the validity of the DSR testing mode, four different test protocols were run, including a frequency sweep test at different temperatures and temperature ramping at a fixed frequency with different temperature rates. This experiment was applied to three different bituminous binders, two non-modified binders, soft and hard, and a standard Polymer modified Bitumen (PmB). The analysis was conducted on shear modulus and phase angle versus Temperature. The outcomes showed a reasonably good correlation between the different protocols in the common range of temperatures and demonstrated instrument limitations regarding geometry and control parameters.

The use of Reclaimed Asphalt (RA) into new asphalt mixtures becomes an inevitable step for sustainable infrastructure. Saving natural, non-renewable materials, such as bitumen and aggregates, the asphalt industry is moving forward with more recycling. Although asphalt is a 100% reusable material, high recycling rates are not yet easily achievable due to many limitations, going from technical specifications through RA properties to asphalt plant capabilities. The rate of RA, which may be used within a new asphalt mixture, depends on many aspects: variability, moisture and fines contents, presence of polymers, brittleness of aged binder, etc. The latter is directly linked to the degree of the RA binder ageing. As higher RA content increases the asphalt mixture stiffness, the material becomes more brittle and prone to cracking. The use of recycling additives is taking recycling to the next level by solving these issues. With the growing need of the industry for asphalt recycling agents, many products have appeared on the market with different effects. In this study, three asphalt recycling agents (two industrial and one alternative) were used as rejuvenators. Blends with 50% of rejuvenated RA binder (RAb) and virgin binder were subjected to different ageing levels: short (RTFOT), long (PAV for 20 h) and prolonged (PAV for 60 h). After each ageing level, physical, rheological and chemical properties were evaluated addressing the ageing behaviour of the additives used. Testing results showed that one industrial additive lost almost all its properties after prolonged ageing, whereas the other additives showed comparable results with the second industrial product.

The present paper describes the rutting behavior of innovative mixes incorporating 50% of Reclaimed Asphalt (RA) with bio-materials. They were assessed in the laboratory and in a full-scale accelerated experiment. The innovative mixes studied here contained bio-materials especially designed to help recycling by re-activating the aged binder from RA. Four mixes were evaluated: three of them are manufactured with bio-materials, (two bio-rejuvenators and one bio-binder) and one was a control mix, which was a high modulus asphalt mix (EME2). In this study, the rutting resistance of the four mixes was first evaluated in the laboratory with both European and US methods. The full-scale test was then performed in order to evaluate the rutting resistance of the bio-recycled asphalt mixes under heavy traffic (200,000load cycles loaded at 65kN) and compared with the control one. A simplified analysis leads to the conclusion that, with the Nantes climate, a daily traffic of 150heavy vehicles per day applied over 20years corresponds to approximately 200,000heavy vehicle loads when the surface temperature exceeds 30°C. Therefore, it can be considered that the rutting evaluation made on the carrousel represented almost 20years of traffic during hot-day periods. The results obtained on the test track were consistent with the laboratory rutting tests showing good performance for all the mixes. The materials presenting the best performance on the test track also presented the best performance in the laboratory.

The use of rejuvenators has seen a consistent increase over the years in the asphalt pavement industry. This is due to the need for maximizing the demand for incorporating a higher amount of Reclaimed Asphalt (RA) in the pavement asphalt mixtures. In order to tackle this challenge, the Task Group 3, focusing on asphalt binders and additives, of the RILEM TC RAP conducted an interlaboratory activity to evaluate the effect of aging on blends of virgin and rejuvenated RA binders. A set of conventional tests including penetration value at 25 °C, softening point temperature and rheological measurements by means of Dynamic Shear Rheometer (DSR) were selected to involve a large number of participants. A binder, recovered from field RA, was treated with a bio-based rejuvenator and blended with a virgin binder to simulate recycling at three different percentages 60, 80, and 100%. These blends, as well as the pure virgin binder, were next short and long term aged and tested to evaluate the changes in the corresponding properties. Relatively consistent results were obtained for the entire set of blends. The aging of combined rejuvenated RA and virgin binders was comparable to that experienced for the pure virgin binder. DSR data provided a more precise evolution of the impact of aging on the materials.

In this paper, the combined effect of aging temperatures and cooling medium on the rheological properties of asphalt binder was experimentally investigated and evaluated. Two 70/100 penetration gra...

The RILEM TC 272 PIM (Phase and Interphase behavior of innovative bituminous Materials)—TG1 Binder has initiated an inter-laboratory program investigating the phase and interphase behaviour of bituminous binders. Within the scope, four laboratories evaluated the low temperature properties of seven binders with differential scanning calorimetry (DSC). DSC has been accepted as a powerful tool to evaluate, among others, the glass transitions, Tg, monitoring the endothermic or exothermic heat flow of a material under controlled temperature conditions. There are different ways to run the test, conventional temperature linear-DSC (TL-DSC), and temperature modulation-DSC (TM-DSC). The latter has been proven as an efficient method differentiating the structural relaxation phenomena from the heat capacity. In this study, emphasis was placed on comparing the Tg measured by TL- and TM-DSC to improve the interpretation of binder glass transitions. In this study, the scope was restrained to two Polymer modified Binders (PmBs): a commercially available modified binder named PmB1 and a highly modified binder (7.5 wt% high vinyl SBS) named PmB2, were evaluated and compared with two neat bituminous binders. Based on the thermographs of the PmB2 obtained through this inter-laboratory program, it was observed that the modification by 7.5% SBS resulted in a decrease of the Tg. This reduction of Tg reflects the positive influence of SBS at low temperatures.

The recent drive to find ways to increase sustainability and decrease costs in asphalt paving has led researchers to find innovative ways to incorporate more recycled materials and bio-derived binders into mixes with varying success. A new novel bio-derived binder made from refined pine chemistry stabilised with a polymer can increase the sustainability of asphalt mixes while maintaining pavement performance. Laboratory performance testing was conducted on asphalt mixes containing 50% Reclaimed Asphalt Pavement (RAP) by mix weight and the novel bio-derived binder. Results show that the bio-derived binder outperforms the conventional 50/70 pen grade binder mixes with respect to resistance to thermal cracking and adequately passes all requirements for pavements with 20-year design loadings of less than 30 million ESALs. This research shows that asphalt mixes containing 50% RAP and a bio-derived binder can be designed to pass performance criteria at low, intermediate, and high temperatures without the need of neat bitumen.

Due to emerging climate challenges, engineers are looking to replace the conventional asphalt pavements by utilizing bio-materials combined with Reclaimed Asphalt (RA). However, there is insufficient record in the literature assessing their environmental performance. This study addresses the analysis of the results obtained from a life cycle assessment exercise of asphalt pavements containing bio-materials and RA within their binder courses, developed within the BioRePavation project. The aim is to analyze the environmental benefits achieved, by means of hotspot mapping and sensitivity analysis of the most impactful factors of their lifecycles. Two alternatives are compared to a conventional asphalt pavement and recommendations on how to improve the current practices are provided. Results rank the raw material acquisition and replacement as the most impactful stages, while through sensitivity analysis, linear relationships between the impact category indicator values and the RA% used, are detected.

In the last years, the constant shift in bituminous binder sources and qualities have increased interest in identifying new products that can enhance the properties of bitumen. This study is a broa...

With modern recycling technologies, reclaimed asphalt (RA) has been successfully used in new hot mix asphalt (HMA). However, even if the conventional technical specifications on binders and asphalt mixtures are met, HMA produced with high amount of RA, 50% and higher, may show poor performance behaviour. This is particularly true for cracking susceptibility due to the different chemical and physical properties of aged bituminous binder. The benefit of a purposely designed rejuvenating agent can help in using a high amount of RA in new HMA. This paper presents an evaluation of asphalt mixtures comparing a virgin asphalt mix with 0% RA and mix with 70% of RA with and without a bio-based rejuvenating agent. The different asphalt mixtures were characterised with complex modulus measurement at different temperatures and frequencies, and low-temperature cracking susceptibility through the thermal stress restrained specimen test. The binder was extracted and recovered from the different mixes to be also investig...

Properties of asphalt mixtures after ageing are fundamental parameters in determining long-term performance (e.g. durability) of these materials. With increasing popularity of reduced temperature mixtures, such as warm-mix asphalt, WMA, the question remains how a reduction in short-term ageing affects the properties after long-term ageing of bituminous materials. This paper aims to improve our understanding of the effect of asphalt manufacturing temperature on ageing and the resulting mechanical properties of bituminous binder by studying the effect of short- and long-term ageing of different bitumen samples as a function of short-term ageing temperatures. For this purpose, round robin experiments were conducted within the RILEM technical committee (TC) 252 chemo-mechanical characterisation of bituminous materials by 10 laboratories from 5 countries using four binders of the same grade (70/100 pen) from different crude sources. The short-term ageing was carried out using the standard procedure for rolling...

Airport pavements have been historical designed with empirical methods such as ACN-PCN method. Over the last decade, more analytical methods have emerged to answer concerns from the use of increased airplane sizes. FAARFIELD in the US or Alize Airport in Europe are comprehensive tools to design and predict pavement behaviour for various airplane categories. With the configuration of the super jumbo jets with high weight/high tire pressure, such as A380, B787, the pavement structure behaves differently and, in some cases, suffers particular surface cracking out of the wheel path. This was observed during the Accelerated Pavement Testing program carried out for the evaluation of the A380 impact on pavement. Thanks to the pavement analytical tools, a deeper analysis of strain distribution, within the whole pavement structure, shows that, while the main fatigue design criteria is still at the bottom of asphalt layers, the pavement surface can suffer as well from fatigue cracking. The top layer materials have to contribute both to the resistance to permanent deformation, and to the resistance to fatigue cracking under heavy loading/high-pressure tires. This means, large airport facilities require the use of specifically designed asphalt materials with enhanced characteristics against rutting and fatigue.

On mature road networks, there is a constant need for long-term pavement preservation solutions. In the 1980s, SBS polymer brought a breakthrough technology with superior performance for surface layer. In more recent years, highly modified asphaltic binder, HiMA, took a step further for structural layers with fatigue resistance. At the same time, circular economy enhances the valorisation of Reclaimed Asphalt. However, its reuse in top layers is challenging, as RA may deteriorate cracking resistance. This paper presents results of laboratory evaluation of an asphalt mix combining 25% RA and the use of highly modified bitumen with 7.5% specific SBS polymer and compared with a same mix using a normal Polymer modified Bitumen 25/55-55. The evaluation was carried out with compactability, rutting resistance, complex modulus, fatigue and low temperature cracking susceptibility. From the mixes, binders were extracted and recovered for further evaluation similarly to the asphalt mixes. This study demonstrated the benefits of both standard PmB and highly polymer modified bitumen to achieve high performance asphalt mix combined with RA. The HiMA binder was able to restore, to a greater extend, the lost properties against cracking and still maintaining the benefits in terms of rutting resistance. This emphasises the benefit for PmB usage for both structural and surface layers, even when using Reclaimed Asphalt, for sustainable modern asphalt pavements.

The present paper describes the full-scale accelerated test, carried out on asphalt pavements made up with bio-materials, especially designed to help reusing Reclaimed Asphalt (RA) by re-activating the aged binder. Four pavement sections were evaluated: three pavement sections with innovative bio-materials (bio-recycled asphalt mixtures), and a reference section with a conventional, high modulus asphalt mix (EME2). In this study, fatigue resistance was first evaluated in laboratory, with two-points bending test, and then at full scale under heavy traffic loading, with the IFSTTAR accelerated pavement testing facility. The evolution of bio-materials recycled asphalt mixture characteristics, as well as the pavement distresses, were recorded and analyzed. The structural condition of the pavement sections was monitored periodically through falling weight deflectometer (FWD) measurement as well as with strain gauges and temperature sensors. Although the reference EME2 mix presented the highest fatigue resistance in laboratory, on the full scale test, the three bio-based asphalt mixtures performed similarly or better than the control EME2 mixture.

This paper evaluates whether the temperature reduction production during Warm-Mix Asphalt (WMA) leads to a beneficial effect on short- and long-term aging properties of asphalt binder. For this purpose, two 70/100 penetration grade virgin asphalt binders were used. First, the material was short term aged at three different temperature, 123 °C, 143 °C, and 163 °C, and then, long term aged. Shear complex modulus was then measured with the Dynamic Shear Rheometer and the data used to generate master curves and fit the 2 Spring 2 Parabolic 1 Dashpot model. Glover–Rowe parameter and crossover-temperature were next determined to further investigate the effect of aging temperature on the properties of the material. Significant differences were observed between 163 and 123 °C for both short- and long-term aging conditions. However, a remarkable difference between 143 and 123 °C could be detected only for the short-term aged binder. Finally, the statistical analysis confirmed the experimentally observed trend. Based on the results and analysis presented in this paper, it can be hypothesized that a reduction in the temperature of short-term aging, which is commonly experienced during WMA production, may result in an overall substantially milder aging.

This recommendation reports on the effect of the Rolling Thin Film Oven Test (RTFOT) aging temperature on chemo-mechanical properties of asphalt binders for Warm Mix Asphalts. The RTFOT testing temperature should ideally replicate physical and chemical short-term aging of asphalt mixtures. The relevance of this was investigated in light of the increased use of warm mix asphalt technologies. The recommendations are based on round robin experiments performed by nine participating laboratories and consisting of a series of tests including experimental results on penetration, softening point temperature, Fourier Transform Infrared Spectroscopy and Dynamic Shear Rheology. The results indicate that the current RTFOT aging temperature does not replicate the aging in the mixture. For this reason, the TC recommends the selection of appropriate RTFOT aging temperatures in order to simulate binder aging as a result of various mixing technologies. The sulfoxide index is proposed as a measure of oxidative short term RTFOT aging.

Given the importance of overcoming the challenges associated with the management of nonrenewable resources, and to solve the industrial waste stream problems, this article presents the results of f ...

As more reclaimed asphalt pavement (RAP) is utilised in asphalt mixtures, there are increasing concerns about the potential negative effect of the aged RAP binder on the field performance, especially cracking resistance, of the high RAP mixtures. To address the concerns, there have been increasing interests in utilising rejuvenators to improve the cracking performance of high RAP mixtures. The objective of this study was to determine the benefits of using a new rejuvenator made from renewable sources in asphalt mixtures with high RAP contents. The study was conducted by determining and comparing the laboratory performance properties of three mixtures and the binders extracted from the mixes. The three mixtures evaluated in this study included two 50% RAP mixtures (RAP binder ratio = 0.55) with and without the rejuvenator and a comparable virgin mix. Results of this study suggested that the new rejuvenator was effective in improving both the intermediate and low-temperature cracking performance characteris...

Properties of asphalt concrete after aging are important parameters in determining the long-term performance of these materials. With the popularity of reduced temperature mixtures the question remains how this reduced temperature in short-term aging affects the long-term properties. This paper focuses on developing a robust and fundamental understanding of the effect of temperature on aging by connecting the chemistry of bitumen to its mechanics. To this end, round robin experiments are being currently conducted within 8 laboratories using four binders of the same grade 70/100 pen from different crude sources. In developing chemo-mechanical characterization techniques at the nano- and micro-scale, the material’s variability from crude-source to crude-source and its sensitivity to temperature needs to be taken into consideration. Furthermore, the development of uniform specimen preparation procedures for these bituminous materials at the nano- and micro-structural level is the focus. The chemical characterization is performed using Fourier transform infrared spectroscopy (FTIR). For the mechanical characterization rheological data is used using the dynamic shear rheometer (DSR) as well as conventional tests, e.g. needle penetration and softening point using the ring and ball method. It is shown that the short-term aging temperature affects the increase in softening point, while the consequent effect on long term aging is less pronounced.

An experimental study was conducted to evaluate the effectiveness of two bio-additives as rejuvenators on the properties of asphalt mixtures containing 50% RAP and their binder constituents containing 37% RAP binder. Before mixing, the rejuvenators were blended with fresh bitumen and the extracted and recovered RAP bitumen, and changes in the rheological properties of the binders were assessed using performance grading (PG) criteria. The results showed that both rejuvenators could improve the low-temperature performance of the aged RAP binder and restore its low-temperature properties. Master curves for the unaged, RTFO-aged, and PAV aged blends were constructed using both the Christensen-Anderson-Marasteanu (CAM) model and the Sigmoidal models. A comparative statistical analysis conducted on the models indicated no significant difference between the measured and predicted complex modulus values at any aging conditions. The pairwise statistical comparison between the two models showed that at unaged conditions, they can perfectly overlap as the p-values were greater than the level of significance. However, for the PAV-aged binders, this behaviour appears to weaken due to the brittle behaviour of the binders. Further statistical analyses revealed no significant differences between the two models at unaged conditions, however, as the binders where subjected to aging, significant differences between the two models began to appear. Mixing was performed in two locations: lab and plant, while compaction was performed only in the lab. After mixing and compaction, mixtures were evaluated for their stiffness characteristics through dynamic modulus testing. Compared to the control mixture, rejuvenated mixtures showed lower dynamic modulus values specially at high temperatures. A statistical comparison between the lab-produced, lab-compacted mixtures and plant-produced, lab compacted mixtures showed that both the rejuvenation and the location of mixing were significant factors in the stiffness measurements.

Three innovative environmentally friendly pavement materials, designed with 50% of Reclaimed Asphalt and three different biomaterials (2 bio-additivated bitumens and 1 bio-binder), were produced in an industrial plant. These mixes were tested in lab and also at full scale using an Accelerated Pavement Test facility. The asphalt mix viscoelastic properties were measured in lab and their intrinsic viscoelastic response were simulated. These rheological models are used to simulate the pavement mechanical response using both elastic and viscoelastic multilayer codes. Hence, full scale measurement performed during the full scale test at an early stage (without damages) can be compared with these simulations. The overall prediction accuracy, when all the signals are considered, is between 4% and 8% for all materials. It can be concluded that material characterisation in lab as well as the selected models are well adapted to simulate actual loading state under a moving load, even for these non-conventional mixes. For temperatures lower than 25°C, elastic modelling appears to be sufficient for pavement structural design with the innovative materials tested here.

Recycling of asphalt has become a well-established practice in many countries, however the road pavement industry remains a bulk consumer of extracted raw materials. Novel solutions that find root in circular economy concepts and life-cycle approaches are needed in order to enable optimisation of infrastructure resource efficiency, starting from the design stage and spanning the whole value chain in the construction sector. Itis within this framework that the present study presents a full-scale validation of asphalt mixtures specifically designed to ensure durability of flexible road pavements and at the same time enabling the reuse of reclaimed asphalt pavement (RAP) through the incorporation of bio-materials as recycling agent. These bio-recycled asphalt mixtures have been first designed in laboratory and subsequently validated in a real scale experiment conducted at the accelerated pavement testing facilities at IFSTTAR. Four pavement sections were evaluated: three test sections with innovative bio-materials, and a reference section with a conventional, high modulus asphalt mix (EME2). Two tests were realized: a rutting test and a fatigue test and for each of them the evolution of bio-recycled asphalt mixtures properties as well as the pavement deteriorations were recorded and studied. Evolution of the bio-asphalt mixtures was monitored for a 5 months period after paving by a bespoke nondestructive micro-coring, extracting and recovering methodology developed at the Western Research Institute (WRI). The structural health of the pavement sections was monitored through periodic falling weight deflectometer (FWD) as well as with strain gages and temperature sensors. As a result the three tailored bio-asphalt mixtures performed similarly or better than the control mixture, both in terms of property evolutions and durability.

These recommendations are based on the results of a round robin test organised by the RILEM technical committee TC 237-SIB "Testing and characterization of sustainable innovative bituminous materials and systems". The Task Group 1 (TG1) focused on binder testing. The aim of the TG1 was to further understand the fundamental mechanism of water interaction in asphalt mixture, and to review the various test methods available to evaluate the affinity of bituminous binders to aggregate surfaces. A total of 13 laboratories participated, running different test methods. Three bituminous binders and four aggregate types were selected for testing. These recommendations focus on the main aspects related to testing procedure, measurement and presentation of results. While some qualitative trends are observed, there is still a wide scattering in results both within the same test method and between test methods. This is not only related to a visual interpretation of the degree of bitumen coverage, but also theoretical and numerical analyses of test results. The overall recommendation is to consider the results within qualitative classes.

Oxidative ageing is an important phenomenon affecting asphalt concrete. Currently, binder short-term ageing, occurring during mixture production and laying, is simulated worldwide through rolling thin film oven test (RTFOT), which was developed assuming that the mixture is produced at conventional hot mix asphalt (HMA) temperatures around 160 °C. However, since ageing is strongly influenced by temperature, lower production temperatures imply less material ageing so that the introduction of warm mix asphalt (WMA) technologies could potentially require some adjustments in the ageing simulation procedures. This study aims at determining which RTFOT temperature simulates WMA short-term ageing more closely. To this end, the chemical and the mechanical characteristics of one type of bitumen, recovered from two asphalt mixtures (WMA and HMA) prepared and short-term aged in laboratory, were compared to those of the same virgin binder short-term aged in laboratory with RTFOT at different temperatures (123 °C and 163 °C). Both conventional and rheological tests show higher ageing levels for the binder recovered from HMA with respect to the binder aged with RTFOT at 163 °C, whereas the binder recovered from WMA generally provides an ageing level lower than the binder aged with RTFOT at 163 °C. These results are also confirmed by the chemical analysis using FTIR which indicate higher oxidation levels for the hot mix process compared to the warm mix. These preliminary results confirm that it is necessary to identify an appropriate ageing temperature for the short-term ageing simulation of WMAs with RTFOT.

The use of Dynamic Shear Rheometer, DSR, has become a standard testing method to address the rheology of bituminous binder in various conditions. This test can generate a comprehensive set of data. Its interpretation can be done in different ways, depending on what will be the key features to address. This paper provides an overview and put in perspective the different parameters and approaches when analysing DSR data. It is based on a selection of different paving grade binders from soft to hard, one Polymer modified Binder and different aging conditionings of a standard binder. The analysis includes master curve of complex shear modulus, Black Space, Cole Cole diagram, as well single associated parameters such as Performance Grade criteria, cross-over parameters, Glover-Rowe parameter, amongst over. They all provide relevant and complementary information. While considered alone, they are not sufficient to address the whole range of behaviour. The combination of them can give a broader view of binder behaviour.

Oxidative ageing strongly affects asphalt mixture behavior. The Rolling Thin Film Oven Test (RTFOT) is currently used to simulate within a laboratory environment the binder short-term ageing, assuming that the mixture is produced at conventional Hot Mix Asphalt (HMA) temperatures (ca 160 °C). However, the introduction of Warm Mix Asphalts (WMAs), which are produced at lower temperatures than HMAs, could require adjustments in the short-term ageing simulation procedure as ageing is strongly influenced by the mixing and compaction temperatures. In this study, the physical properties of a straight-run bitumen, before ageing and after RTFOT ageing at two temperatures (123 °C and 163 °C), are compared to those of the same bitumen recovered from a HMA and a foamed WMA, both produced in laboratory. This comparison aims at determining the best RTFOT temperature for short-term ageing simulation for WMAs. To this end, all the binders were investigated through conventional (penetration value at 25 °C and softening point temperature) and rheological (frequency sweeps with dynamic shear rheometer) tests. Both conventional and rheological tests indicate that the WMA recovered binder is less aged than the binder aged at the standard conditioning temperature of 163 °C, whereas the HMA recovered binder is more aged than the artificially aged binder in the laboratory with RTFOT at 163 °C. These initial results support the idea that an appropriate ageing temperature for RTFOT short-term ageing simulation of WMA needs to be identified.

This paper presents the preliminary experimental activity conducted to develop the round robin test (RRT) plan on the use of rejuvenators for the Task Group (TG) 3 on Asphalt Binder for Recycled Asphalt Mixtures as part of the RILEM TC 264-RAP. For this purpose, a reference Reclaimed Asphalt (RA) binder was extracted from a single RA source. This material was then fully characterised with conventional experimental methods and with Fourier Transform Infrared Spectroscopy (FTIR) for evaluating the chemical structure. The RA binder was found to be very hard compared to target binder of PEN50/70 grade and the use of virgin binder cannot restore its properties. In this condition, a rejuvenator dosage of 9% per weight of RA binder is foreseen as optimum value to restore the binder properties close to target PEN50/70 grade for the final binder-rejuvenator blend over a RA content ranging from 60% and 100%.

The Rilem Technical Committee on Chemo Mechanical Characterization of Bituminous Materials has investigated the effect of short term aging temperature on long term properties of asphalt binder, chemically, physically and microstructurally. The increased use of warm mix asphalt (WMA) technologies warrants such investigations in order to validate laboratory aging procedures. To this end, penetration, softening point, Fourier Transform Infrared Spectroscopy, dynamic shear rheology (DSR) and electron microscopy (ESEM) were used. The experimental results on binders and warm (WMA) and hot (HMA) mixtures from nine participating laboratories indicate that the binder source, as well as method of evaluation, result in different rankings and behaviors among the four binders used. The TC recommends the development of appropriate RTFOT aging temperatures for the simulation of binder aging in WMA.

This RILEM round robin study with nine participating laboratories investigated bitumen ageing, its effect on chemical properties and its reproducibility. The impact of temperature used for short-term (RTFOT) binder ageing on the combined short- and long-term (PAV) aged samples was investigated; thereby the effect of reduced mixing temperature such as those relevant for warm mix asphalt technologies on long term ageing was examined. Four 70/100 penetration graded bituminous binders from different sources were selected. In addition to the standard RTFOT temperature of 163 °C, two additional temperatures, 143 and 123 °C were used. The Fourier transform infrared spectroscopy (FTIR) analysis was carried out using an integration method which considers the area below the absorbance spectrum around a band maximum using baseline and tangential approaches. A statistical investigation into the reproducibility of FTIR spectra analysis based on the accumulated data was done. To assess the reproducibility, the coefficient of variation (CV) was taken as a benchmark parameter. Carbonyl and sulfoxide indices were calculated using different baseline correction methods and tangential and baseline integration, respectively. It was shown that the tangential method was not influenced by the applied baseline correction. However, in all considered cases, the tangential method led to significantly worse reproducibility (CVs ranging from 20 to 120%) compared to the baseline method. The sulfoxide indices calculated by both methods were not affected by the baseline correction method used. Impacts of changes in the short-term ageing temperature on short- or long-term aged samples could not be found whereas differences between different binder sources could be detected. RTFOT temperature and therefore mix production temperature had a stronger impact on the formation of sulfoxide structures than for carbonyl structures. The findings from this study show the most reproducible of all considered methods when more than one laboratory is providing FTIR data.

Recycling of old pavements is becoming a widespread technique; in order to preserve the natural resources of aggregates and binder, the materials reclaimed from the damaged layers of the pavements maintained are generally reincorporated in the material for new maintenance layers. However, recycling induces some technical challenges. In the case of the Hot mix asphalt (HMA), the most commonly used road construction material, one of the main concerns is ageing. Along with the heterogeneity of the RA properties in stockpiles, it is one of the main factors limiting the recycling rates in HMA. Therefore, the characterisation of ageing through reliable ageing indexes and of its impact on the bitumen physical properties is of paramount importance to improve the recycling techniques. The RILEM TC 237 SIB TG5 inherited a database from the previous work of the RILEM TC 206 ATB TG5 on a protocol for bituminous mixture ageing in laboratory. Taking advantage of these data, the work of the Task Group was first dedicated to a state of the art and an evaluation of the chemical ageing characterization through indexes based on Fourier Transform Infrared Spectroscopy (FTIR). In a second step, an attempt was made, in order to bring out the essential trends of the rheological data with ageing, by using a Huet modified rheological model. Then, exploring the potential of a recently developed method, an interpretation of these trends in terms of asphalt structure is suggested. Finally, possible empirical relationships between the chemical ageing indexes and the rheological parameters are investigated.

Pavement durability is often linked with water damage either through raveling or loss of integrity, especially considering asphalt materials. A large number of tests exist to address the water sensitivity and affinity between aggregates and asphalt binder. In Rilem TC 237 SIB, TG1 looked at the common test methods used to evaluate the adhesion or affinity of asphalt binder to aggregate surfaces. One of the main purposes was to run a Round Robin Test to evaluate the reproducibility and repeatability of these test methods and to give recommendations for improvement. Three asphalt binders were selected, two unmodified and a polymer modified binder and four aggregate types with different mineralogy. This paper presents the first results obtained for the rolling bottle test. The influence of aggregate type is higher than that of the asphalt binder. While there are some potential trends after 24 h comparing the different combinations of aggregate and binder, there is still a lot of variability in the absolute results. The underlining reasons are not yet clearly identified.