Experimental Investigation and Prediction of the Conventional Properties of Sustainable Asphalt Binder Mastic Modified with Calcined Red Mud

In the past, studies have reported the production of asphalt binder mastic with red mud as filler, culminating in improved mixture performance. However, this involves repetitive laboratory testing, which can be both time-consuming and resource-intensive. Therefore, this work predicts the performance of calcined red mud-modified asphalt binder mastic using response surface methodology (RSM). The red mud was calcined at 400 ° C, 500 ° C and 600 ° C, used as filler in asphalt binder mastic at filler-to-binder ratios of 0.6, 0.8 and 1.0, and its effects on mastic conventional properties, moisture susceptibility and short-time aging resistance were investigated. In the RSM analysis, the independent variables considered are red mud content and degree of heat treatment, while the dependent variables include the mastic conventional properties (penetration, softening point and penetration index), moisture susceptibility and short-time aging resistance. The experimental results show that penetration decreases and the softening point and penetration index increase with increasing filler/binder ratio and calcination temperature, demonstrating improved performance. The developed model showed R 2 values of 0.9374, 0.9616, 0.9532, 0.8813, and 0.9398 for softening point, penetration, penetration index, stripping rate, and AIC, respectively, indicating good predictability. An optimal value of filler-to-binder ratios of 1.0 and calcination temperature of 427.46 ° C resulted in 65.15 ° C, 37.04 dmm, 1.32, 0.146 and 0.12 for softening point, penetration and penetration index, stripping rate and AIC, respectively. The optimised of asphalt binder mastic properties will provide a practical screening tool for both asphalt mixture design and direct industrial applications.