Enhancing Asphalt Performance with Industrial Waste: A Study on Red Mud as a Filler Replacement

The increasing demand for sustainable construction practices has encouraged the use of industrial waste as an alternative to conventional materials in asphalt mixtures. One such industrial waste is red mud a highly alkaline and fine-grained residue by-product of alumina production from bauxite ore. This study evaluates the mechanical properties of asphalt mixtures containing red mud, focusing on Marshall and volumetric properties and key performance indicators such as indirect tensile strength, tensile strength ratio, resilient modulus, indirect tensile fatigue, and dynamic creep. The results indicated that red mud can be used as a complete (100%) replacement for conventional filler in asphalt mixtures and still meets the required specifications outlined in the Marshall mix design, moreover, no significant differences (p-value of 0.981) in optimum binder content (OBC) were observed among the mixtures, indicating that red mud as a filler does not impact binder content or increase costs. Red mud improved asphalt performance, with Mix-RM3 showing the highest indirect tensile strength, increasing by 21% (dry) and 23% (wet) compared to Mix-RM0. Mix-RM2 achieved the best tensile strength ratio, 7.1% higher than Mix-RM0. Resilient modulus increased with red mud content, peaking at Mix-RM4 with a 10% improvement over Mix-RM0. Asphalt mixtures containing red mud as a substitute for traditional filler exhibited a significant improvement in fatigue resistance and dynamic creep performance. According to the ranking evaluation, the optimal red mud content was 50–75% of the filler, yielding superior mechanical properties compared to other levels.