The Impacts of Red Mud on Road Performance and Aging Resistance of Asphalt Mixture

ABSTRACT Red mud as an asphalt modifier has been investigated in some studies, but few studies are further concerned about the effect of red mud on performance of asphalt mixture. In this study, the impact of red mud on road performance and aging endurance of asphalt mixtures was evaluated. Primarily, the optimal asphalt content was determined based on mechanical strength and volumetric properties. Then, the performance evaluations, including Marshall stability, low-temperature splitting, freeze-thaw splitting, indirect tensile fatigue, and thermal-oxidative aging, were executed. The outcomes demonstrate that in comparison with the base asphalt mixture, red mud asphalt mixture exhibits worse high-temperature stability and moisture resistance, and superior temperature shrinkage cracking resistance and fatigue performance. After the surface of red mud has been modified, the adhesion between asphalt mastics and aggregate is strengthened, and the distribution of red mud in asphalt mixture becomes more uniform, which intensifies the rigidity and road performance (except for low-temperature cracking resistance) of asphalt mixture. Furthermore, since red mud absorbs a portion of asphalt content, it can hinder the physical hardening and oxidation rate of asphalt mixture. The anti-aging ability of asphalt mixture is further reinforced by the incorporation of organic red mud.