Application of organic red mud in SBS-modified asphalt mixture: Influence on road performance and thermal-oxidative aging resistance

The deterioration of road performance in asphalt mixtures due to aging can significantly affect the service period of asphalt pavement. Therefore, it is particularly important to find a suitable method to resist the aging of asphalt mixture. In this study, various red mud-compounded styrene-butadiene-styrene (SBS)-modified asphalt mixtures were prepared using acid-treated and surface-modified raw red mud (RM) as a modifier for SBS-modified asphalt. First, SBS-modified asphalt mixture specimens were prepared at the optimal oil-rock ratio. Subsequently, both unaged and aged mixtures were subjected to Marshall stability, low-temperature splitting, freeze-thaw splitting, and indirect tensile fatigue tests to evaluate the effect of different red muds on the road performance of SBS-modified asphalt mixtures. The experimental results showed that the addition of raw red mud (RM) improved the high-temperature performance, moisture susceptibility, and fatigue performance of SBS-modified asphalt mixtures, but adversely affected their low-temperature performance. The high-temperature stability, moisture susceptibility, and fatigue performance were further enhanced with the incorporation of organic red mud. Additionally, raw red mud effectively delayed the thermal-oxidative aging of the mixture. After surface modification, red mud can significantly enhance the thermal-oxidative aging resistance of the SBS-modified asphalt mixture. Among the tested samples, the mixture incorporating red mud treated with oxalic acid and titanate coupling agent exhibited the highest durability against aging.