Asphalt pavements are prone to aging in construction and during service, which can affect the properties of the asphalt. The aging behaviors of high content crumb rubber modified asphalt (HCRMA) were investigated in this paper. The binders were aged in the laboratory and the performances before and after aging were tested using the attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) test, temperature sweep (TS) test, frequency sweep tests, multiple stress creep recovery (MSCR) test, zero shear viscosity (ZSV) test, bending beam rheometer (BBR) test, and linear amplitude sweep (LAS) test. The FTIR test result shows that as the aging progresses, the crumb rubber (CR) continues to undergo desulphurization and degradation reactions in the HCRMA, with the release of substances such as silica and S-C bonded material from the CR into the bituminous phase. The elasticity of HCRMA decreases and then increases as the degree of aging increases. Besides, the low temperature performance of HCRMA is controlled by the stiffness value, and the low temperature stress relaxation properties of HCRMA in the aging process are better than that of 20% content crumb rubber modified asphalt. Moreover, aging can reduce the integrity and fatigue resistance of HCRMA while increasing the compatibility of HCRMA.

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High content rubber modified bitumen (HCRMB) prepared from the high content of waste tire rubber and bitumen has good performance while allowing greater use of the waste tires. However, HCRMB is subject to aging during use, which can affect its performance. The purpose of this paper was to investigate the effect of high content of waste tire rubber and sulfur on the aging behavior of bitumen. The properties of all bitumen were tested using rolling thin film oven aging (RTFOT) test, pressure aging vessel (PAV) test, frequency sweep tests, temperature sweep (TS) test, multiple stress creep recovery (MSCR) test, and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) test. Test results show that the addition of sulfur to HCRMB leads to an improvement in the elasticity of HCRMB. The elasticity of HCRMB with different amounts of sulfur increases with aging. In addition, the increase in the amount of sulfur can improve the RTFOT aging resistance and the PAV aging resistance of HCRMB. Sulfur cannot reduce the degree of oxidation of HCRMB after aging, but can inhibit the degree of desulfurization of HCRMB. Furthermore, the aging process of HCRMB with different amounts of sulfur is dominated by the degradation of polybutadiene.

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The influence of sulfur on the chemical, rheological, and aging resistance of terminal blend rubberized bitumen (TBRB) was studied. TB hybrid bitumen (TBHB) was prepared from with different sulfur contents (0.1, 0.2, 0.3, 0.4 wt%) and TBRB prepared with neat bitumen and crumb rubbers at 20% content. TBHB binders were aged by rolling thin film oven test (RTFOT) and pressure aging vessel (PAV), respectively. The chemical composition of TBHB binders was monitored by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Rheological properties of all TBHB samples were tested. Chemical composition results show that TBHB can inhibit the degradation of polybutadiene compared with TBRB in the RTFOT stage, and the polybutadiene degradation is the main process of TBHB in the RTFOT stage, while the TBHB is mainly desulfurized after PAV aging. Meanwhile, the increase in sulfur content in the TBHB can improve the desulfurization degree of the TBHB binder after PAV. TBRB containing sulfur can improve the mechanical properties and elasticity and reduce the hardening degree during aging. Moreover, blending sulfur into the TBRB caused a lower complex modulus aging index after aging, which indicates that TBHB has superior aging resistance@en

The high viscosity and poor storage stability of crumb rubber-modified asphalt (CRMA) can be partially addressed by the appropriate degree of degradation of the crumb rubber modifier. However, the low-Temperature and fatigue characteristics of degraded crumb rubber-modified bitumen (DCRMB) in different aging states are not well understood. In this study, two types of DCRMB-namely, terminal blend rubberized asphalt (TBRA) and terminal blend hybrid asphalt (TBHA)-were prepared with sulfur, styrene-butadiene-styrene (SBS) polymer, and crumb rubber (CR). All DCRMB binders were short-Term aged with a rolling thin film oven test (RTFOT) and long-Term aged with a pressure aging vessel (PAV). Afterward, a bending beam rheometer (BBR) test and a linear amplitude sweep (LAS) test were conducted to characterize the low-Temperature and fatigue properties of DCRMB binders at different aging degrees, respectively. Based on the rheological test results, several conclusions can be drawn. First, the BBR results indicated that the increase in CR content led to a slight increase in creep rate and a significant decrease in stiffness. Especially in PAV aging, the low-Temperature properties of DCRMB were much better than those of neat asphalt. Meanwhile, DCRMB demonstrated an advantage over neat asphalt in integrity and fatigue resistance before and after aging. Finally, based on correlation analysis, the LAS test is recommended for evaluating the fatigue properties of DCRMB before and after aging.

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Terminal blend rubberized asphalt (TBRA) is widely used as binder of asphalt mixtures due to its technical characteristics of storage stability. However, its road performance deteriorates due to the aging process of TBRA. The purpose of this study is to evaluate the aging characteristics of TBRA binders containing 0%, 5%, 10%, 15%, and 20% content of crumb rubber (CR) by weight of the neat binder. All the binders were treated with rolling thin-film oven test (RTFOT) and pressure aging vessel (PAV), respectively. The chemical compositional changes were monitored by attenuated total reflection (ATR)-Fourier transform infrared spectroscopy (FTIR), and physical and rheological properties were tested on neat asphalt and TBRA binders. FTIR test results show that TBRA binders offer greater long-term aging resistance than the neat asphalt binder, and E10TB (10% by weight CR) exhibits the highest long-term aging resistance. With the increase of CR, the temperature sensitivity property of the TBRA binders increases, whereas their high-temperature stability decreases. After PAV aging, blending CRs into neat asphalt causes a higher phase angle aging index and Jnr aging index, and lower critical temperature aging index, complex modulus aging index, softening point increment, and rutting factor aging index, indicating their superior long-term aging resistance. Moreover, based on the correlation analysis, the critical temperature aging index (CTAI) has a good linear relationship with the physical aging index (SPI) and chemical aging index (δICA).

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