Aging Characteristics of Rubber Modified Asphalts in Different Environmental Factors Combinations

Two kinds of rubber modified asphalts were investigated and compared with virgin asphalt. In order to get closer to engineering practice, different combinations of four environmental factors were merged into the laboratory aging simulation. Subsequently, conventional property tests, including softening point, viscosity, creep stiffness, creep rate, and fatigue cracking were conducted on asphalt samples. The performance difference of asphalt before and after aging was selected as an evaluation index for asphalt aging degree. The results indicate that two kinds of rubber modified asphalts show stronger resistant ability to temperature deformation and better resistance to traffic loading than virgin asphalt in all kinds of environmental factors combinations. Tests on chemical analyses were conducted to investigate the asphalt aging characteristics. The apparent morphology of rubber modified asphalts are described in detail under an environment scanning electron microscope (ESEM). The damage condition reflected in images reveals the aging degree caused by multiple environmental factors. Moreover, the thermogravimetric analysis (TG) confirms that three kinds of asphalts can maintain thermal stability in various environments. Additionally, new characteristic functional groups were not detected in the infrared (IR) spectra of rubber modified asphalts, which means they have stable antioxidant properties given that their oxidation degrees change slightly throughout the aging processes.