Low-Temperature and Fatigue Characteristics of Degraded Crumb Rubber-Modified Bitumen Before and After Aging

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.