Utilization of red mud as an alternative mineral filler in asphalt mastics to replace natural limestone powder.

• Replacement of limestone powder by red mud made the asphalt mastic stiffer. • Adding red mud resulted in reduced cracking resistance, moisture damage resistance and fatigue life. • The utilization of red mud has proved to be practicable by adding a certain amount of white mud as the modification agent. With the view of reducing the consumption of non-renewable limestone resources, the waste-derived secondary resource can be considered as the limestone powder replacement for hot asphalt mixtures. This study unravels the feasibility of using a red mud-derived alternative filler aggregate to replace the commonly used limestone powder in asphalt mastics, and further improves the red-mud-modified asphalt mastic by using hydrated lime and white mud. The experimental tests, including direct tension (DT), Positest AT-A bonding strength, as well as dynamic shear rheometer (DSR), were performed to characterize the cracking resistance, the moisture damage, the fatigue behavior, as well as the rheological properties of asphalt mastic. Due to surface morphology and mineralogical composition of red mud, its replacement of limestone powder improved the elastic recovery of asphalt mastic, but it had detrimental effect on properties of the cracking resistance, the moisture damage and the fatigue life. When incorporating the hydrated lime and white mud, both materials can improve the low-temperature cracking resistance of red mud asphalt mastic. Moreover, the incorporation of the white mud into the red mud asphalt mastic can enhance its moisture resistance of aggregate-mastic bonding under both short- and long-term moisture attack as well as its fatigue resistance. [ABSTRACT FROM AUTHOR]