Low-temperature Performance Of Asphalt Binder Research Articles

An efficient and robust method for evaluating the low-temperature performance of asphalt binder based on DSR testing

The BBR test has received growing concerns regarding its applicability to field studies and special materials due to the large amount of long-term aged asphalt binder used in preparing asphalt binder beams and the time-consuming beam preparation and testing process. In recent years, the application of a dynamic shear rheometer (DSR) to investigate the low-temperature performance of asphalt binder has attracted widespread attention because it uses significantly less asphalt binder for testing and allows for easy specimen preparation. The objective of this study was to develop an efficient and robust method to evaluate the low-temperature performance of asphalt binder based on DSR testing. Frequency sweep tests were performed on twelve asphalt binders at temperatures ranging from 0 to 25 °C using the 8-mm parallel plate geometry. Two conversions were applied to frequency sweep test data in order to predict the flexural creep stiffness and m-value of asphalt binder, namely the conversion from frequency domain to time domain and the conversion from shear loading to bending loading. The 1S2P1D model was employed to construct the master curves of storage modulus and loss modulus. Afterwards, the flexural creep stiffness was predicted using the shear creep compliance master curve model, which was derived from the 1S2P1D model using the inverse Laplace transform, and the Poisson’s ratio, which was assumed to be constant. It was found that the predicted values of S(60) and m(60) were comparable to the counterparts measured by the BBR, which well demonstrated the feasibility of the proposed DSR-BBR conversion method. In comparison to existing analysis methods, the proposed conversion method strictly complied with the linear viscoelastic theory, and it enabled efficient and robust predictions because the prediction model of flexural creep stiffness had the same parameters as those of the 1S2P1D model, thus avoiding multiple data fittings.

Effect of polyisobutylene on low-temperature thermoreversible aging properties in asphalt binders

In order to study the influence of polyisobutylene (PIB) on pavement performance of asphalt binders, two asphalt binders with large differences in wax content and the similar performance grades were selected as the base asphalt binders, and three kinds of waxes and PIB were selected as additives. Extended bending beam rheometer (Ex-BBR) test, double-edge-notched tension (DENT) test, multiple stress creep recovery (MSCR) test and rotational viscosity test were used to study the effect of PIB on the low, medium and high temperature properties of asphalt binders, respectively. The phase transition pattern of PIB when interacting with waxes was analyzed by variable temperature polarizing microscope (VT-PLM). The results show that PIB can be miscible with waxes and reduce the melting point of waxes by about 20∼60%. PIB can improve the low-temperature performance (reducing creep stiffness), medium-temperature performance (increasing toughness and fracture resistance), high-temperature performance (improving high-temperature deformation resistance and deformation recovery ability) and workability (reducing mixing and compaction temperature) of asphalt binders (including high-wax and wax-based warm-mixed asphalt binders). It is worth noting that PIB will aggravate the thermoreversible aging (the results of P-value analysis showed that PIB had a significant effect on the grade loss (GL) of asphalt binders), which will affect the low-temperature performance of asphalt binders during the isothermal low-temperature storage, resulting in premature damage to the pavement.

Mechanism of physical hardening on the fracture characteristics of polymer-modified asphalt binder

This article aims to reveal the physical hardening mechanism of polymer-modified asphalt binder (PMA) and accurately assess its impact on the low-temperature fracture properties of asphalt binders. Base asphalt binder (BA), styrene–butadiene–styrene modified asphalt binder (SBSMA), and crumb rubber modified asphalt binder (CRMA) were used as the research objects. Molecular dynamics (MD) simulation and differential scanning calorimetry (DSC) test were used to investigate the physical hardening mechanism of PMA at the microscopic level. The fracture characteristics of PMA under physical hardening were analyzed based on the single-edge notched beam (SENB) test. The results show that under prolonged cold service conditions, the asphalt molecular mobility is weakened, the non-bond energy and the free volume are reduced, and the molecules undergo aggregation state transformation, leading to the physical hardening of asphalt materials. In the process of physical hardening of asphalt molecules in the micro-Brownian motion of the main active force from the aromatic and saturate fractions. Considering the effect of physical hardening, it is recommended that the method used to test the low temperature properties of asphalt binders should ensure a constant temperature for at least 24 h. The crack tolerance (Ct) is recommended as the evaluation index of low-temperature cracking resistance of PMA in cold regions. The Ct of BA, SBSMA, and CRMA are reduced by 52.88 %, 12.04 %, and 35.24 %, respectively, after 24 h of constant low temperature. This indicating that the polymer modifiers can improve the fluidity of asphalt molecules, inhibit molecular aggregation, and reduce the effect of physical hardening on asphalt binders. Thermo-oxidative aging can aggravate the physical hardening phenomenon of asphalt binder, and the higher the degree of thermo-oxidative aging, the more severe the physical hardening of asphalt binder. The related research results provide the theoretical basis and technical support for the accurate design and development of the low-temperature performance of asphalt binders for roads in cold regions.

Investigation on physical properties and modification mechanisms of diatomite/SBR modified asphalt.

In recent years, diatomite has been successfully adopted in asphalt modification to overcome the problems of polymer modified asphalt, because of the advantages in wide sources, low price, and worthy technical characteristics. Although the improvement of the high-temperature performance of the modified diatomite asphalt has been verified in previous studies, the diatomite will bring negative impact on the low-temperature resistance. Hence, the objective of this study is to seek a new channel to improve the comprehensive performance of the diatomite modified asphalt binder. Considering the advantage of the SBR in improving the low-temperature performance of asphalt binder, the diatomite/SBR composite modified asphalt binder (DSA) and the corresponding preparation technology are developed to obtain an improved comprehensive performance via the orthogonal experiment method in this study. Moreover, the modification mechanisms of the DSA are revealed using fluorescence microscopy (FM) tests, Gel permeation chromatography (GPC) tests, and Fourier transform infrared spectroscopy (FTIR) tests.

Evolution of Low-Temperature Properties of Warm-Mix Rubber-Modified Asphalt under Freeze–Thaw Cycles

Confocal scanning laser microscopy (CLSM), Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) were performed to analyze the changes in apparent morphology, the functional groups, and glass transition temperatures of warm-mix rubber-modified asphalt under freeze–thaw cycles to describe the evolution mechanism of the low-temperature performance of asphalt binders under freeze–thaw cycling at the microscale level. Using the bending beam rheometer (BBR) test, the relaxation and delay characteristics of the asphalt binders under freeze–thaw cycling were quantitatively analyzed using the parameters fitted by Burgers model, and based on the dynamic shear rheometer (DSR) test, the low-temperature evaluation indices of the asphalt binders were calculated using the Christensen–Anderson–Marasteanu (CAM) model. Regression analysis of the related performance parameters was carried out, so as to describe the evolution of the low temperature performance of asphalt under freezing-thawing cycles at the macroscopic level. It was indicated that freeze–thaw cycling reduced the low-temperature performance of the asphalt binders. Compared to water freeze–thaw cycling, salt freeze–thaw cycling caused a greater degree of damage to the surfaces and changes in the related parameters of the asphalt binders. Also, the addition of warm-mix additives (EM and SDYK) changed the low-temperature performances of the rubber-modified asphalt (60MCR). After freeze–thaw cycling, the rubber-modified asphalt with SDYK (0.6S-60MCR) showed lower degrees of change of characteristics describing low temperature performance than those of the rubber-modified asphalt (60MCR) and rubber-modified asphalt with EM additive (1E-60MCR), indicating its superior resistance to anti-cracking ability at low temperatures.

Reclamation of waste oils in asphalt modification towards enhanced low-temperature performance of pavement in cold region

ABSTRACT To decrease the usage of petroleum asphalt and improve waste recovery, two different groups of recycled oils were selected to improve the low-temperature performance of asphalt binders in cold region. The multiple stress creeps recovery (MSCR) test, linear amplitude sweep (LAS) test and bending beam rheometer (BBR) test were performed to evaluate the rheological properties of recycled oil modified asphalt (ROMA). The thermal stress and double edge notched tension (DENT) tests were employed to characterise the low-temperature cracking resistance and ductile resistance of the ROMA, respectively. The results of this study showed that recycled oils significantly improved the low-temperature and fatigue performance of asphalt, which is manifested in a drop in the low-temperature critical cracking temperature of asphalt by 3°C, increase in crack tip opening displacement (CTOD) by 72.8%, and extension of fatigue life by 178.9%. The addition of recycled oils reduced the percentage of large molecule size (LMS) while increasing the percentage of medium molecule size (MMS) of the asphalt, which contributes to the better low-temperature performance of the ROMA. The results from this study provide insights into the reclamation of waste oils and developing the low-temperature modifier of asphalt pavements in cold region.

Rheological properties of asphalt binder modified by nano-TiO2/ZnO and basalt fiber

Nanomaterials and fibers have gradually become widely used modifiers in asphalt to improve the performance of pavements. However, studies have been focusing on the improvement of individual properties, while comprehensive analyses are still not available. In this study, different contents of nano-TiO2/ZnO and basalt fiber were used to prepare composite-modified asphalt binders. Using scanning electron microscopy (SEM), dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests, Fourier transform infrared (FTIR) spectroscopy, and other experimental methods, the rheological properties and microstructure of modified asphalt binders were determined. The tests results indicate that incorporation of nano-TiO2/ZnO and basalt fiber can significantly improve the high-temperature performance and fatigue life of composite-modifier asphalt binder before aging and after short-term, long-term, and ultraviolet (UV) aging. In addition, an improved permanent deformation resistance was obtained for asphalt pavement with basalt fiber and nano-TiO2/ZnO additives. However, low-temperature performance of asphalt binder was weakened by the addition of basalt fiber, while the appropriate amount of nano-TiO2/ZnO could eliminate negative effects. Moreover, the FTIR results suggest that there was no chemical reaction between basalt fiber, nano-TiO2/ZnO, and asphalt, and the modification mechanism is mainly of physical nature. Furthermore, the nanoparticles were more evenly distributed in the asphalt, which, together with the basalt-fiber-forming network structure hindered the propagation of internal microcracks. The conclusion of the tests is that the optimal content of nano-TiO2/ZnO is 4 wt% of the asphalt, while the content of basalt fiber is 6 wt%.

Rheological evaluation of asphalt binder modified by amorphous poly alpha olefin (APAO)

This study examined the effect of amorphous poly alpha olefin (APAO) on the rheological behavior of asphalt binder. In order to modify asphalt binder, several percentages of APAO (0, 2, 4, 6, 8%, and 10% by the weight of asphalt binder) were used. The penetration grade, softening point, ductility, and viscosity tests were performed. Also, the multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests were conducted to evaluate the rutting and fatigue behavior of asphalt binder. The storage stability test was implemented to measure the ability of modified asphalt binder against separation. Based on the results, using APAO reduced the penetration grade and increased the softening point due, maybe, to the asphalt binder stiffening. The PI values increased with the addition of APAO, which indicated that the temperature susceptibility of all modified asphalt samples was reduced compared to the base asphalt binder. The increase in the viscosity of virgin asphalt binder due to APAO addition caused the mixture placement/compaction operations to become harder. The G*/sinδ parameter for all types of pre-post-aging RTFO asphalt binders was improved for APAO-modified asphalt binder, meaning that the latter stiffened and thus increased the respective rutting resistance of mixtures. The low-temperature performance of asphalt binder indicated that the stiffness of asphalt sample increased with an increase in the APAO percentage, which indicates that the addition of APAO improved the cracking potential of modified asphalt binders and had negative effects on the asphalt binders. The storage stability test results indicated that the phase separation of asphalt binder was related to the APAO content. Results revealed, ignoring the levels of stress, that using APAO reduced the non-recoverable creep compliance (Jnr) value of virgin asphalt binder, indicating the production of an asphalt binder benefitting higher rutting resistance with APAO modification. APAO increased the %R of asphalt binder. Based on the LAS test results, the addition of APAO led to an increase in the fatigue life of asphalt binders, and by increasing the additive content, the fatigue life increased. The FTIR analysis indicated that no chemical interaction was observed between asphalt binder and APAO.

Thermoreversible aging in model asphalt binders

Thermoreversible aging is an important factor leading to premature cracking in asphalt pavement. In order to better understant the contribution of various pure waxes in asphalt binder to thermoreversible aging, model asphalts are prepared with three kinds of alkanes (eicosane, triacontane, and squalane). The effects of alkane dopant crystallization on the thermoreversible aging properites of low- and high-wax asphalts are examined using extended bending beam rheometer (ExBBR) test and limiting phase angle temperatures. The results show that eicosane is an additive that improves the conventional 1 h low-temperature performance of asphalt binder, but it will aggravate the thermoreversible aging and the magnitude depends on the base asphalt and concentration of additive. The branching of straight-chain hydrocarbons can improve the low-temperature performance of the corresponding asphalt without aggravating the degree of thermoreversible aging. Limiting phase angle temperature is more sensitive to the dosage of C30 and squalane additives. But poor correlation is found for C20 doped asphalts.

Predicting the low-temperature performance of asphalt binder based on rheological model

At present, the test methods to evaluate the low-temperature performance of asphalt binder focus on bending beam rheometer (BBR), and dynamic shear rheometer (DSR) is mainly used for high-temperature and medium-temperature tests. The reason is that when the test is in the low-temperature range, the instrument compliance errors are an unavoidable problem in DSR test. To solve this, based on the frequency sweep test of DSR, the modified Havriliak-Negami (MHN) model was employed to deduce the temperature at which asphalt binder undergoing the glass transition, and the torsion cylinder (TC) test and differential scanning calorimeter (DSC) were conducted to verify its correctness. Furthermore, the relationship between this approach and the low-temperature performance of asphalt binder is established by nonlinear fitting and linear regression analysis. This study presented an approach to predict the low-temperature performance of asphalt binder based on rheological model, which provides a solution to the difficulty of evaluating the low-temperature performance of asphalt binder using DSR.

Carbon Nanomaterials for Enhancing the Thermal, Physical and Rheological Properties of Asphalt Binders.

Effective thermal conduction modification in asphalt binders is beneficial to reducing pavement surface temperature and relieving the urban heat island (UHI) effect in the utilization of solar harvesting and snow melting pavements. This study investigated the performance of two nanometer-sized modifiers, graphene (Gr) and carbon nanotubes (CNTs), on enhancing the thermal, physical and rheological properties of asphalt binders. Measurements depending on a transient plant source method proved that both Gr and CNTs linearly increased the thermal conductivity and thermal diffusivity of asphalt binders, and while 5% Gr by volume of matrix asphalt contributed to 300% increments, 5% CNTs increased the two parameters of asphalt binders by nearly 72% at 20 °C. Meanwhile, a series of empirical and rheological properties experiments were conducted. The results demonstrated the temperature susceptibility reduction and high-temperature properties promotion of asphalt binders by adding Gr or CNTs. The variation trends in the anti-cracking properties of asphalt binders modified by Gr and CNTs with the modifier content differed at low temperatures, which may be due to the unique nature of Gr. In conclusion, Gr, whose optimal content is 3% by volume of matrix asphalt, provides superior application potential for solar harvesting and snow melting pavements in comparison to CNTs due to its comprehensive contributions to thermal properties, construction feasibility, high-temperature performance and low-temperature performance of asphalt binders.

RETRACTED ARTICLE: Influence of crumb rubber particle sizes on rutting, low temperature cracking, fracture, and bond strength properties of asphalt binder

The present study aimed at evaluating the effect of Crumb Rubber (CR) particle size on rutting, low temperature cracking, fracture, and bond strength properties of asphalt binder. Three different CR particle sizes (#10–20, #30–40, and #60–80) were considered in this research work. Rutting performance was evaluated using Multiple Stress Creep Recovery (MSCR) tests. Although the addition of CR was found to improve the rutting performance, asphalt binder combination with higher CR particle size exhibited better performance compared to asphalt binder combination with lower CR particle size. Similarly, low temperature cracking properties were evaluated using Bending Beam Rheometer (BBR). It was found that the addition of CR has positive impact on the low-temperature performance of asphalt binder. Fracture property was evaluated using Double Edge Notch Tension (DENT) test and found to be improving with the increase in CR particle size. Finally, the effect of CR particle size on moisture damage resistivity potential was evaluated using the recently developed Bitumen bond strength (BBS) test. Although the addition of CR was found to have deteriorating impact on bond strength behavior, the degree of impact was found to be lower for asphalt binder containing the lowest considered CR particle size.

Investigating the potential of using dry battery waste powders (DBWPs) as a modifier for asphalt binders

This study aims at investigating the potential of using dry battery waste powders (DBWPs) as modifiers in asphalt binder. A 60/70 penetration grade asphalt binder was used in this study. DBWPs, which were extracted from spent batteries, were mixed with the asphalt binder at seven different percentages [0% (control sample), 2%, 4%, 6%, 8%, 10%, 15%, and 20% by weight of asphalt binder]. The mixing process was performed at 175 °C for 30 min using a high-speed mechanical mixer. To study the effect of DBWPs on asphalt binder properties, both traditional and Superpave binder tests were carried out. Consistency tests included penetration, softening point, and ductility, while Superpave tests included Rotational Viscometer (RV), Dynamic Shear Rheometer (DSR), and Bending Beam Rheometer (BBR). Flash and fire point tests were also conducted. The test results indicated that the addition of DBWP to the asphalt binder decreased ductility and penetration values and increased the softening and the flash and fire points of the asphalt binder. High-temperature rutting performance of asphalt binder, as presented by DSR rutting parameter (G*/sinδ), was improved by adding DBWP. The high-temperature performance grade of asphalt binder was raised by one grade by adding DBWP up to 10%, two grades at 15%, and three grades at 20%. On the other hand, fatigue and low-temperature performance of asphalt binder were adversely affected by adding DBWP. The Superpave fatigue parameter (G*.sinδ) was negatively increased by increasing the content of DBWP but remained less than the Superpave limit (≤ 5000 kPa). The low-temperature asphalt binder grade was decreased from − 22 °C (for control asphalt binder) to − 16 °C at 15% DBWP and then to − 10 °C at 20% DBWP. Therefore, it is recommended to use DBWP modifier in high-temperature regions to resist rutting distresses.

The potential use of recycled polyethylene terephthalate (RPET) plastic waste in asphalt binder

The current study aims to examine the potential use of recycled polyethylene terephthalate (RPET) plastic waste as a modifier for asphalt binder. Plastic bottles were collected, shredded, cleaned, melted, ground, then sieved. An asphalt binder with a penetration grade of 60/70 was used. The RPET plastic waste was blended with 60/70 penetration grade asphalt binder at five percentages (0, 5, 10, 15, and 20 %, by weight of asphalt binder) using a high shear mixer. To study the physical and mechanical properties of RPET-modified asphalt binders, both traditional and Super pave tests were conducted. The test results showed that by incorporating RPET into asphalt binder, the ductility and penetration values decreased, whereas the softening point and viscosity of asphalt binder increased. Furthermore, the rutting performance of RPET-modified asphalt binder, as presented by the rutting parameter (G*/sinδ), was enhanced by increasing the amount of RPET plastic waste at all testing temperatures. The high-temperature performance grade of asphalt binder was raised by one grade (from 64°C to 70°C) by adding 15% and 20% of RPET plastic waste. On the other hand, the low-temperature performance of asphalt binder, as presented by creep stiffness and m-value, was negatively affected by adding RPET. The low-temperature performance grade of asphalt binder was dropped by one grade (from −22°C to −16°C) by adding RPET plastic waste at percentages of 15 % and 20 %. Moreover, the fatigue cracking performance of asphalt binder, as presented by the fatigue parameter (G*.sinδ), was slightly reduced by adding RPET to the asphalt binder but remained lower than the acceptable Super pave limit (≤ 5000 kPa).

Investigating Low-Temperature Properties of Nano Clay–Modified Asphalt through an Energy-Based Approach

Abstract Significant effort has been given by researchers in recent years to explore the potential use of nanomaterials such as nano clay (NC) for asphaltic pavement applications. The effect of NC on fatigue and rutting performance of asphalt binder has been reported by many researchers; however, limited information is available regarding its effect on the low-temperature performance of asphalt binder. Besides that, reported work reflects inconsistent conclusive remarks about the influence of NC on low-temperature performance parameters of asphalt binder. Therefore, this study examines the effects of NC on low-temperature properties of asphalt binder not only through a conventionally adopted approach (on the basis of creep stiffness and creep rate) but also a dissipated energy-based approach. NC dose was selected as 0, 2, 4 and 6 % by the weight of the asphalt binder. Initially, creep stiffness and relaxation rate were evaluated as per the recommendation of ASTM D6648, Standard Test Method for Determining the Flexural Creep Stiffness of Asphalt Binder Using the Bending Beam Rheometer (BBR). Although the creep stiffness value was found to increase, the creep rate was found to decrease only by a marginal amount with incremental dosages of NC. A master curve was subsequently drawn for creep stiffness, relaxation modulus, and creep rate, and the curve indicated their strong dependency on the level of creep period. Furthermore, various energy parameter components were evaluated with the help of viscoelastic modeling of creep compliance response using the Burgers model. Although both the energy components were found to decrease with NC addition, the rate of decrease in the dissipated energy component was higher compared with the corresponding decrease in stored energy with incremental dosages of NC. Such a response indicated a decrease in overall stress relaxation rate and hence degradation of low-temperature properties of control binder with the addition of NC to asphalt binder.

Relations between colloidal indices and low-temperature properties of reclaimed binder modified with softer binder, oil-rejuvenator and polybutadiene rubber

Asphalt binder properties play an important role in the behavior of asphalt concrete pavements at low temperature and should be studied using laboratory tests. This research investigates the relationship between chemical properties and low-temperature performance of asphalt binders at RAP contents of 15%, 30%, 50 and 100% by weight. The asphalt is also modified with a softer binder, oil rejuvenator and polybutadiene rubber (PBR 1220) modified binder. Binder testing includes penetration test, softening point, bending beam rheometer (BBR) and Fraass breaking point. Moreover, saturate, aromatic, resin, and asphaltene (SARA) fractionation is used to study the induced changes in the chemical composition of binders after adding RAP. The results show that binders modified with oil-rejuvenator have better resistance to low temperature cracking in comparison with softer binder and polymer modified binder (PMB), particularly at high percentages of RAP. Using a softer virgin binder also demonstrates improvements in the low-temperature performance of RAP binder. Moreover, PBR 1220 blended with RAP binder showed poor resistance to low-temperature cracking, it means that having a low Tg (for polymer) would not necessarily lead to a good low temperature cracking of the polymer-modified binder. Finally, some promising statistical correlations are found between colloidal indices and low-temperature performance of samples with RAP content.

Effects of Electronic Waste Powder on Asphalt Binder Properties

Asphalt binders for various types of pavement construction that were modified with various contents of electronic waste powder (EWP) were characterized. The effects of EWP content on asphalt physical properties, storage stability at high temperatures, dynamic rheological parameters, and low-temperature cracking resistance were studied. Chemical properties of modified mixtures were studied using IR spectroscopy. Experimental results showed that EWP did not react chemically with the asphalt binder Studies of the physical properties of mixtures showed that EWP additives could increase significantly the high-temperature asphalt performance. Studies of storage stability showed that modified mixtures were highly stable with EWP contents <20%. If the EWP content was increased, the complex shear modulus of modified asphalt increased whereas the phase angle decreased significantly. On the other hand, bending beam rheometer (BBR) tests showed that EWP additives did not improve the low-temperature performance of asphalt binder.

Low-temperature rheological behavior of ultraviolet irradiation aged matrix asphalt and rubber asphalt binders

In order to investigate the influence of ultraviolet (UV) irradiation aging on the rheological properties of asphalt binders at low temperatures, this paper analyzes the low-temperature rheology characteristics (stiffness modulus S and tangent slope m) of matrix asphalt and rubber asphalt in the bending beam rheometer (BBR) test. The beam of asphalt binder was shaped in an advanced mold to receive more ultraviolet irradiation. The asphalt samples were subjected to different given UV-irradiation time (50h, 100h, 200h, and 300h) after thin film oven test (TFOT), with an indoor UV-irradiation aging simulation system. As comparative groups, corresponding original samples and thermal-oxidative aged samples from TFOT and pressurized aging vessel (PAV) test were also measured in BBR. Furthermore, based on the viscoelasticity theory, Burgers model was utilized to describe the constitutive relationship. In order to achieve a global solution, genetic algorithm (GA) was adopted for the nonlinear regression of viscoelasticity parameters (Ee, Ed, η1, and η2) under different aging conditions. The results show that TFOT-UV aging had a different influence on the matrix asphalt and rubber asphalt. The effect of TFOT-PAV aging to the (relative variation ratio of) viscoelastic parameters was equivalent to that of TFOT-UV aging during the irradiation time less than 100h to the rubber asphalt. Along with the UV-irradiation time increasing, the S increased and m decreased, therefore, the low-temperature performance of asphalt binders became worse.

Evaluate thermal cracking resistance of asphalt binder using 4-mm dynamic shear rheometer monotonic test

ABSTRACTThis study was conducted to evaluate the thermal cracking resistance of asphalt binder using monotonic test by 4-mm dynamic shear rheometer (DSR). The asphalt binder used in this study was extracted and recovered from four field sections of Rochester experimental pavement in Olmsted County, Minnesota. Fracture energy and failure strain obtained from the stress–strain curve were found to be potentially good indicators to investigate low-temperature performance of asphalt binder. It was observed that the fracture energy and failure strain correlate well with transverse thermal cracking in the field. The frequency sweep test to determine shear modulus and the bending beam rheometer (BBR) test to determine the creep stiffness and m-value were conducted to verify the test result.

Analysis of different indices for high- and low-temperature properties of asphalt binder

The high- and low-temperature performance of asphalt binders have an important effect on the rutting and cracking resistance of asphalt pavements, thus these are two of the most important performance of asphalt binders. Nowadays, there are many indices to evaluate the high- or low-temperature performance of asphalt binders respectively. But there is still no unified option about which index is better.As a kind of typical viscoelastic materials, both of the high-temperature performance and the low-temperature performance of asphalt binders are related to viscoelastic characteristics of asphalt binders, but they are opposite to each other. That is, a binder needs to have more elastic part for high-temperature performance but more viscous part for low-temperature performance. So the ratio of viscous part to elastic part is important to high- and low-temperature performance of asphalt binders. Based on that thought, a new index based on viscoelastic characteristics, referred to as RJ, is developed in this study. Different high- and low-temperature evaluation indices including RJ were analyzed by comparing the performance ranking evaluated by them with the ranking of the corresponding mixtures. The correlation between performance of binders evaluated by different indices and the performance of the corresponding mixtures were also analyzed. Based on the results, zero shear-rate viscosity and non-recoverable stiffness is found to be suitable for evaluating the high-temperature performance of asphalt binders, stiffness at 60s from BBR is found to be suitable for evaluating the low-temperature performance of asphalt binders. The established evaluation index, RJ, is found to be suitable for evaluating both performances of asphalt binders.