BBR Test Research Articles

Effects of the chemical structure of curing agents on rheological properties and microstructure of WER emulsified asphalt

Current researches in the pavement engineering field are neglecting the influence of the chemical structure of curing agents on rheological properties of waterborne epoxy resin (WER) emulsified asphalt. The length of molecular chain and the number of active groups will affect the rigidity and flexibility of WER emulsified asphalt. In this study, three curing agents (TETA\DETA\593) with obvious differences in molecular chain length and number of active groups were selected to modify emulsified asphalt. The three kinds of WER emulsified asphalt were subjected to the conventional properties, DSR, BBR, SEM and FITR test. The research has found that the addition of WER system makes emulsified asphalt produce three-dimensional network structure, which significantly improves the high-temperature performance and temperature sensitivity of emulsified asphalt. Whereas, the low-temperature performance of WER emulsified asphalt deteriorates. This indicates that the high-performance of WER emulsified makes it more suitable for the adhesive of micro surfacing or cold mix asphalt used in heavy-load traffic in medium and high temperature areas. Curing agent TETA has the greatest impact on WER emulsified asphalt at high-temperature while 593 has the least adverse influence on the low-temperature performance. The results demonstrate that the more active groups in the curing agent, the higher the crosslinking degree and complexity of the three-dimensional network structure in WER emulsified. And it will lead to the better high-temperature performance of WER emulsified. The longer the molecular chain of curing agent, the more flexible chains in WER emulsified. And it will lead to better flexibility of WER emulsified.

Effective volume filling ratio of siliceous fillers within bituminous composites: experimental and micromechanical modelling

The effect of different volume filling ratios (VFR) of filler on the flexural creep stiffness and complex shear modulus of bituminous composites can be identified using BBR and DSR test setups. This research compares the findings of extensive experimental studies with the biphasic heterogeneous micromechanical finite element (FE) models to introduce the Effective Volume Filling Ratio (EVFR). The different VFRs from 10 to 40% were selected to fabricate asphalt mastic samples. The effects of loading regime, temperature, loading frequency, and VFR on the mechanical behavior of asphalt mastic were investigated, and practical formulations were proposed to determine the EVFR for both shear and bending stiffening. It was found that for VFR ≤ 20%, the differences between the FE and test results are negligible under both loading schemes. However, higher VFRs cause a further increase in the stiffening and percolation effects which produce more differences between the experimental and FE results.

Effect of Polypropylene Grafted Maleic Anhydride (PP-G-MAH) on the Properties of Asphalt and its Mixture Modified With Recycled Polyethylene/Recycled Polypropylene (RPE/RPP) Blends

In this study, a ternary blend modifier (TBM) was prepared with RPE, RPP, and various dosages of PP-g-MAH (i.e., 0%, 1%, 3%, 5%, 7%, and 9% by weight of RPE and RPP) by a twin-screw extruder. The performance of TBM (4% by weight of asphalt) modified asphalt was studied, with the increase of PP-g-MAH content, the penetration decreases gradually, but softening point and viscosity increases and ductility exists minimum value at 7% content, with the increasing of PP-g-MAH percentage, the dynamic rheological properties show that |G*| increases, while the δ and |G*|cosδ decrease, and the fatigue performance (|G*|sinδ) of TBM modified asphalt is worse than virgin asphalt. Dynamic stability test shows that TBM shows the prominent high-temperature properties of a modified (asphalt mixture. BBR test indicates that the m-value of asphalt modified with TBM does not fulfill the requirements (m-value>0.3) except at 5% and 7%, but the S meets the standard requirements (S < 300 MPa), and increases from 0% to 7%, then decreases slightly. In order to illuminate possible reasons, a chemical reaction (ester compounds generated) and physical twines of concerned polymer molecules were put forward, and the results were confirmed by infrared analysis.

Aging performance of high viscosity modified asphalt under complex heat-light-water coupled conditions

During the rapid development of sponge city construction in China, the porous asphalt pavement has been widely applied. The high viscosity modified asphalt that is used for producing porous asphalt experiences complex aging circumstances. In this study, the aging performance of high viscosity modified asphalt was evaluated based on the simulated heat-light-water coupled conditions, in which different aging effects and degrees were considered. The complex aging simulation method was innovated that mainly composed of an UV radiator and an environmental cabinet. The dynamic shear properties, high and low-temperature performance, and microstructural morphology of aged high viscosity modified asphalt binders were evaluated through the DSR (temperature-frequency sweep scan, LAS, MSCR), BBR, and ESEM tests, respectively. The results of DSR and BBR test demonstrated that the coupled aging effects should be considered during the service period, since acid rain solution and UV light also led to significant influences on the viscoelastic properties, high and low-temperature performance, and fatigue performance as similar as high temperature. The observation of the microstructures illustrated the aging mechanisms of different environmental factors and their combined effects. This study could provide a better protocol for aging performance examination of high viscosity modified asphalt binder used for porous asphalt pavement considering complicated environmental conditions.

Designing of an anti-rutting and High Ductility Asphalt Mixture based on mortar performance

The anti-rutting and anti-cracking performance of asphalt mixtures are a pair of contradictions that are difficult to coordinate. In order to ensure the rutting resistance of asphalt mixture to meet the requirements of the specification, while improving its deformation capacity and crack resistance. Based on the mortar performance, the Anti-rutting and High Ductility Asphalt Mixture with excellent anti-rutting performance and deformation performance was designed in this paper. With the filler-asphalt ratio as the control index, SBS modified asphalt and SHV modified asphalt was selected to design five asphalt mortars with different filler-asphalt ratios of 0, 0.5, 1.0, 1.5, 2.0. Variation laws of mortar technical indicators were investigated by rotational viscosity test, cone penetration test, and BBR test. Asphalt mixtures were prepared and a rutting test and small beam bending test were carried out to ensure the consistency of the mixture skeleton state by grouting molding. The influence of the mortar performance index on the road performance of the mixture was evaluated by conducting correlation analysis, and then an anti-rutting and high-ductility asphalt mixture was proposed based on mortar performance. The obtained results showed that the technical indicators of asphalt mortar had a good correlation with the filler-asphalt ratio, and the developed regression model could be used to determine the correlation and design of the mortars. The technical performance index of mortar was found to be directly correlated with the road performance index of the mixture. The developed anti-rutting and high-ductility asphalt mixture not only had good anti-rutting performance but also had good deformation capacity and cracking resistance. Its anti-rutting performance could meet the specification requirements, and the maximum flexural strain could reach 7161 με. The performance of asphalt mortar determines the road performance of the mixture. The rutting resistance and cracking resistance of the mixture could be coordinated by designing asphalt mortar to improve its comprehensive road performance. To guarantee that the dynamic stability of the mixture met the required specifications and the deformation ability was good, the critical value of each technical index of asphalt mortar was recommended.

Comparative analysis on rheological characteristics of different modified asphalt based on DSR and BBR evaluation

PurposeIn order to evaluate the rheological properties of asphalt more comprehensively and effectively, and to explore and discuss the practicability of relevant models in the evaluation of the rheological properties of asphalt.Design/methodology/approachBased on the rheological and viscoelastic theories, temperature scanning, frequency scanning and multiple stress creep recovery (MSCR) tests of different modified asphalt were carried out by dynamic shear rheometer (DSR) to obtain relevant viscoelastic parameters and evaluate the high temperature properties of different modified asphalt. Based on the time-temperature equivalence principle, the main curve was constructed to study the viscoelastic properties of asphalt in a wider frequency domain. The main curve was fitted with the CAM model, and the rheological properties of different modified asphalt were evaluated through the analysis of model parameters. The creep stiffness and creep velocity of different modified asphalt were obtained through the rheological test of bending beam (BBR), and the low-temperature performance of different modified asphalt was analyzed by using Burgers model to fit the creep compliance.FindingsThe results show that the high temperature rheological properties of several modified asphalt studied in the test are ranked from best to worst as follows: PE modified asphalt > SBS modified asphalt > SBR modified asphalt. Short-term aging can improve the high temperature performance of asphalt, and different types of modifiers can promote or inhibit this improvement effect. Based on BBR test and Burgers model fitting analysis, SBR modified asphalt has the best low temperature performance, followed by SBS modified asphalt, while PE modified asphalt has poor low temperature performance, so it is not suitable to be used as road material in low temperature area.Originality/valueCombined with effective evaluation methods, the rheological properties of asphalt at different temperatures and angles were systematically evaluated, and the evolution of rheological properties of asphalt characterized by model parameters was further analyzed by advanced model simulation.

Rheological Characteristics of Tire Rubber-Modified Asphalt following Thermal Variation

In recent years, due to the development of the automobile industry, there are more and more waste car tires, and the reuse of waste tires has become an urgent problem to be solved. In this study, the crushed rubber of waste automobile tires is used to modify asphalt to prepare rubber-modified asphalt, which can not only solve the problem of using waste tires but also effectively improve the performance of asphalt pavement. This study defines four modified asphalts with different rubber powder content, which are defined as 1#, 2#, 3#, and 4#, respectively. The performance difference between the four modified asphalts and the base asphalt was compared through experiments to illustrate the advantages of rubber-modified asphalt. The four selected rubber asphalts and base asphalt are subjected to the viscous toughness test, apparent viscosity test, DSR test, and BBR test to determine the high- and low-temperature characteristics of rubber asphalt. The analysis of experimental data shows that rubber-modified asphalt can effectively improve the low-temperature performance of the asphalt, make the asphalt have better toughness, and also improve the high-temperature shear resistance of the asphalt. Finally, it is determined that adding 10% rubber powder to the base asphalt has the best effect.

Effect of co-positivity for brucellosis and tuberculosis on milk yield and fertility of Holstein cows.

This study aimed to determine whether cows detected as tuberculosis (bTB) reactors and seropositive to brucellosis (bBR), as well as co-positive to bBR and bTB (bBR-bTB) and with a complete lactation before slaughter, were associated with reduced milk production and fertility. A total of 8068 productive and reproductive records of high-yielding Holstein cows from a single large dairy herd with a high prevalence of bTB and bBR were collected from 2012 to 2015. Lactation derived either from calving (n = 6019) or hormonally induced lactation (n = 2049), and all cows received growth hormone throughout lactation. For cows not induced into lactation, pregnancy rate to first service for healthy cows (C; 26.6%) was higher (P < 0.01) than bBR (15.2%), bTB (15.8%), and bBR-bTB (1.3%) cows. For induced cows, pregnancy rate to first service did not differ significantly among C, bBR, and bTB (14.5-17.3%) cows, but the percentage success of first service was extremely low (1.3%; P < 0.01) in bBR-bTB cows. Services per pregnancy (only pregnant cows) were lowest for C (3.3 ± 2.9; P < 0.01) and highest (6.4 ± 3.4) for bBR-bTB non-induced cows. This variable was lowest for C (2.9 ± 2.5; P < 0.01) and highest for bBR-bTB non-induced cows (6.3 ± 3.1). Pregnancy rate to all services did not differed for C (79.5%), bBR (76.7%), and bTB (75.9%) but was lower (58.9%; P < 0.01) for bBR-bTB non-induced cows. For induced cows this variable was highest for bBR (53.3%) and lowest for bBR-bTB (34.1%; P < 0.01) non-induced cows. 305-d milk production was increased by 4%, and total milk yield by 7% in TB-positive cows compared to that of the negative cows non-induced hormonally into lactation. This study showed the negative impact of the co-positivity for bTB and bBR on the reproductive efficiency of Holstein cows, although positive bTB and bBR tests enhanced milk yield.

Low-temperature characteristics and microstructure of asphalt under complex aging conditions

In order to study the low-temperature characteristics and microstructure of asphalt under complex aging conditions, ductility test and BBR test were used to study the effects of temperature, aging degree on the low-temperature performance of 90# asphalt and SBS modified asphalt. In addition, the changes of the apparent morphology and microstructure indexes of the two asphalt after aging were observed by the atomic force microscopy (AFM) and Fourier Infrared Spectroscopy (FTIR). The results showed that with the increasing aging degree, the ductility of the two asphalts decreased but the low-temperature critical temperature increased. After short-term aging, the ductility of SBS modified asphalt was always higher than that of 90# asphalt under the same conditions, yet its critical temperature was lower than that of 90# asphalt. As the temperature dropped, the relaxation time gradually increased, and the dissipation energy ratio declined. Furthermore, there were bee-shaped structures with light alternating with dark on the surface of the asphalt. Besides, the increasing aging degree resulted in a decrease in the number of bee-shaped structures, but a more dispersed distribution. During the aging process, the –CH2- and –CH3- contents of SBS modified asphalt changed, and the area ratio at 1376 cm−1 gradually increased after long-term aging and water aging, and reached the minimum after UV aging. In addition, after short-term aging, the SBS modifier degraded at 966 cm−1, destroying the effect of the modifier, and inducing a gradual reduction in its peak area ratio. The above results indicate that SBS modified asphalt has better plastic deformation ability and stronger anti-aging ability. Moreover, ultraviolet radiation has a much larger impact on the low-temperature crack resistance of asphalt than thermal oxidative aging and water aging. Furthermore, the aging mechanism of moisture on the two asphalt is different.

Preparation and performance evaluation of swine manure bio-oil modified rubber asphalt binder

In order to study the effect of the preparation process of swine manure bio-oil modified rubber asphalt binder on the rheological properties of the binder, the matrix asphalt and asphalt rubber were used as the control group, and swine manure bio-oil modified rubber asphalt binders were obtained by three preparation processes. Then the rheological properties of five binders were evaluated by rotational viscosity, DSR, MSCR and BBR tests. The results show that the addition of swine manure bio-oil to asphalt rubber is beneficial to the workability, but cause negative effect on its high temperature performance, fatigue performance and low temperature crack resistance. The preparation method of premixing bio-oil and rubber powder can reduce the degradation of high-temperature performance of asphalt rubber caused by addition of swine manure bio-oil to a certain extent. The fatigue properties of the three bio-binders are close, and the critical temperature is less than 25 °C. The process of premixing bio-oil and rubber powder will increase the creep stiffness and reduce the low-temperature performance. However, the low-temperature performance of the binder obtained by this process is still better than that of the matrix asphalt and can meet the requirements of use. Therefore, it is recommended to use the preparation process of premixing bio-oil and rubber powder to prepare swine manure bio-oil modified asphalt rubber.

Laboratory investigation on the properties of polyurethane/unsaturated polyester resin modified bituminous mixture

As a thermosetting material, unsaturated polyester resin (UPR) can effectively improve the high-temperature stability of bitumen. However, compared with epoxy modified bitumen, UPR modified bitumen has inferior low-temperature crack resistance. Therefore, this paper used polyurethane (PU) to modify UPR, and determined the best formulation of PU/UPR modified bitumen. The properties of PU/UPR modified bituminous binder were evaluated by viscosity, tensile, DSR and BBR tests. Besides, through a series of laboratory tests, the road performances of PU/UPR modified bituminous mixture were comprehensively studied. The results indicate that the PU/UPR modified bituminous binder has better tensile strength and low-temperature performance compared with the pure UPR modified bituminous binder, but the high-temperature stability was slightly worse. After PU addition, the flexural-tensile strength and fatigue resistance of the bituminous mixture were obviously improved, and the low-temperature performance improved slightly. The water stability and oil corrosion resistance almost remained unchanged, and the high-temperature performance was slightly decreased.

Effects of CuO nanoparticles as phase change material on chemical, thermal and mechanical properties of asphalt binder and mixture

Copper oxide nanopowders (Nano-CuO) as phase change material (PCM), Styrene-Butadiene-Styrene (SBS), and carbon nanotubes (CNTs) as a conductive material, were added separately and together in five combination designs to hot mix asphalt (HMA). Controlling the thermal energy transfer was achieved by using Nano-CuO. FTIR analysis illustrated that PCM eliminated the destructive bonds that caused short and long term aging in asphalt binder. From the DSR test results, it was deduced that the modified asphalt binders met the fatigue resistance limit. It was determined that the thermal energy storage (TES) in PCM-modified asphalt binders increased and, also glass transition temperature Tg significantly improved, melting peak temperature Tpm were higher than the pure asphalt binder, and crystallization peak temperature Tpc decreased by 7 °C. According to BBR test results, creep stiffness St and m-value for the modified asphalt binders adhere to the permissible limits at −6 °C. Nano-CuO-modified asphalt binders significantly increased the specific heat capacity Cp of asphalt binders and decreased the temperature and moisture susceptibility. Overall, the combination, including all the three additives, had the most acceptable properties.

Effect of bitumen characteristics obtained according to EN and Superpave specifications on asphalt mixture performance in low-temperature laboratory tests

The paper aims to identify those characteristics of bitumen which have the greatest impact on asphalt mixture low-temperature performance. It was observed that stiffness and m-value of bitumen from BBR test were moderately related to stiffness and m-value of asphalt mixture obtained from 3 PB test. Simultaneously those rheological properties significantly impact on cryogenic stresses induced during TSRST test. The multiple regression model was developed and it implied that mixture failure temperature depends both on rheological properties, brittle fracture and content of bitumen, what means that only comprehensive assessment of bitumen properties enables reasonable assessment of its low-temperature performance.

Prediction of Bending Beam Rheometer Test Outputs Using Artificial Neural Networks

The major objective of this study is to investigate the possibility of using Artificial Neural Networks in creating prediction models capable of estimating Bending Beam Rheometer outputs; namely creep stiffness, and m-value based on test temperature, modifier content; in our case waste vegetable oil, and testing time interval. A feedforward backpropagation neural network with Bayesian Regulation training algorithm and an SSE performance function was implemented. It was found that the neural network model shows high predictive powers with training and testing performance of 99.8% and 99.2% respectively. Plots between laboratory obtained values and neural network predicted outputs were also considered, and a strong correlation between the two methods was concluded. Therefore, it was reasonable to state that using neural networks to build prediction models in order to find BBR test values is justified.

Low- and intermediate-temperature behaviour of polymer-modified asphalt binders, mastics, fine aggregate matrices, and mixtures with Reclaimed Asphalt Pavement material

The long-term effects of SBS-modified binders and rejuvenators on the properties of high-RAP mixtures, especially the cracking resistance, have not been resolved. Therefore, this paper evaluates the cracking resistance of polymer-modified asphalt binders, mastics, fine aggregate matrices (FAMs) and mixtures containing RAP material and a rejuvenator. A series of laboratory tests is performed on different asphalt material scales, including a frequency sweep test; a BBR test for asphalt binders, mastics and FAM mixes; and a dynamic modulus test and the Illinois flexibility index test for asphalt mixtures. Short-term ageing and long-term ageing are also considered for different asphalt material scales. The results show that the asphalt binders and mixes containing RAP materials have similar Glover-Rowe (G-R) values and flexibility index (FI) values to those of the virgin binders and mixtures that are only subjected to short-term ageing. These results indicate that a rejuvenator can partially decrease the stiffness of the RAP material before long-term ageing; however, the cracking resistance of asphalt materials obviously decreases after long-term ageing. Asphalt materials containing RAP are more susceptible than virgin asphalt material to thermal cracking, and the rejuvenator does not improve the long-term cracking resistance of high-RAP material. The correlations between different laboratory ageing conditions for the asphalt binder, mastic, FAM and mixture are analysed. Binders subjected to PAV 20 h ageing present rheological properties equivalent to those of mixes subjected to the long-term oven ageing (LTOA) protocol for 5 d at 85°C. Binders subjected to PAV 40 h ageing present rheological properties equivalent to those of loose mixtures subjected to the LTOA protocol for 12 h at 135°C. The cracking resistance parameters of the binders, mastics and FAMs are also compared with the cracking resistance parameters of the mixture, and the results illustrate that the G-R parameters of asphalt binder, mastic and FAM are well correlated with the G-R parameter and FI parameter of the mixture. Moreover, the G-R parameter can predict the cracking performance of the asphalt mixture.

Low-temperature Performance and its Microstructure of SBS Modified Asphalt under Condition of Aging

The effects of USP warm-mixed agent, Evo warm-mixed agent and aging degree on the low temperature performance and micro-morphology of SBS modified asphalt were analyzed by ductility test, bending creep stiffness test (BBR) and atomic force microscope (AFM) scan test. The test results show that: The ductility test analysis shows that USP warming agent can improve the low temperature performance of SBS modified asphalt in the positive temperature zone, and aging reduces the ductility of warm mixed asphalt, in which Evo warm mix asphalt has the strongest ability to resist thermal aging. BBR test analysis shows that USP warm mixed agent improves the low temperature performance of the negative temperature zone of SBS modified asphalt, but this improvement is limited by the aging effect, the comparison analysis found that creep loading time had a significant impact on the creep compliance derivative, it is more than the effect of warm-mixed agent, and aging can accelerate warm mix asphalt into the creep stability period; AFM micro-scanning found that the "bee-like structure" appeared on the front topography of SBS modified asphalt and Evo warm asphalt. The bee-like structure of Evo warm mix asphalt is larger and more numerous. The larger the size of the bee structure, the smaller the number of bee structures; however, the surface of the USP warm mix asphalt is more undulating; the aging of the two types of asphalt is more serious, and the size of the honeycomb structure is larger, but the number of honeycomb structure is reduced; while the surface of USP warm asphalt is undulating.

Laboratory evaluation on residue in castor oil production as rejuvenator for aged paving asphalt binder

In this study, residue in castor oil production is evaluated as a rejuvenator for aged paving asphalt binder. Different contents of the bio-based rejuvenator, ranging from 0% to 50%, were added to PAV aged binder to prepare samples. DSR tests and BBR tests were carried out to characterize rheological properties of rejuvenated binder. Furthermore, continuous PG grading temperatures were determined from DSR and BBR test data. Test results and data analyses show a notable decrease in complex modulus and an increase in phase angle with increasing rejuvenator content, indicating restoration in viscoelastic properties of the binder. The binder with 30% rejuvenator reaches a level similar to original binder in rutting parameter. The binder with 20% rejuvenator reaches a level similar to original binder in control thermal cracking parameter. The grading temperatures show that all the upper, lower, and intermediate grading temperatures decrease with increasing rejuvenator content, indicating a negative effect on rutting resistance, and positive effects on thermal and fatigue cracking resistances of the binder. The serviceability temperature shows that the gaining in low temperature behavior is more significant than the loss in high temperature behavior, indicating an improving effect of the rejuvenator on temperature susceptibility of the rejuvenated binder.

Using combined Avrami-Ozawa method to evaluate low-temperature reversible aging in asphalt binders

This paper aims to reasonably evaluate the reversible aging resistance of asphalt binders and comprehend the effects of low-temperature gradually hardening on fundamental properties of asphalt binders. To do so, extended bending beam rheometer (ExBBR) test with prolonged different conditioning times were performed on different kinds of asphalt binders, and viscoelastic mechanics model (Burgers model) was employed for describing the rheological properties. The combined Avrami-Ozawa equation was applied to characterise the non-isothermal crystallization process of asphalt binders which have a significantly different degree of physical hardening. The results showed that stiffness or m-value obtained from extended BBR test with logarithmic conditioning time has high coefficient of determination. Predicted stiffness and m-value from proposed empirical formula can be used to estimate extended BBR low temperature limiting grade (LTPG) that could be applicable for quality control (QC) purposes in the future. Lastly, the combined Avrami-Ozawa method can be successfully used to describe the non-isothermal crystallization process of asphalt binders used in this study.

Effect of polystyrene grafted graphene nanoplatelets on the physical and chemical properties of asphalt binder

Polystyrene (PS) grafted graphene nanoplatelets (GNPs) composite (PS-GNPs) was prepared by in-situ polymerization and applied as modifier to Styrene-butadiene-styrene (SBS) for modified asphalt preparation. Specific amount of PS-GNPs incorporation improved ductility, softening point and penetration while DSR, MSCR, BBR and LAS tests showed enhancement in viscoelastic, high temperature rutting resistance performance, anti-fatigue and low temperature performance of the parent asphalt. FT-IR, XRD, SEM and AFM techniques confirmed the successful grafting of PS onto GNPs surface, which increased the interplanar spacing of GNPs with a spring-like macromolecular structure. It was deduced that PS grafted onto GNPs surface dissolved the SBS network in modified asphalt, thus greatly improving its dispersions. This study could be of great help for highway and construction industries.

Aging of Rejuvenated Asphalt Binders

An important concern that limits the RAP content in asphalt mixtures is the fact that the aged binder that is present in the RAP can cause premature cracking. Rejuvenators are frequently added to high RAP mixtures to enhance the properties of the binder. There is no existing method to predict the longevity of a rejuvenated asphalt. This study investigated the aging of rejuvenated binders and compared their durability with that of virgin asphalt. Various samples with different types and proportions of RAP, virgin binder, and rejuvenator were aged by RTFO and three cycles of PAV. DSR and BBR tests were conducted to examine the high-temperature and low-temperature rheological properties of binders. Results indicated that the type and dosage of the rejuvenator have a great influence on the aging rate and durability of the binder. Some rejuvenators make the binder age slower, while others accelerate aging. These observations confirm the importance of evaluating the long-term aging of recycled binders. For this purpose, critical PAV time was proposed as a measure of binder’s longevity.