Valorization of Red Mud Waste for Cleaner Production of Construction Materials

Abstract

Red mud (RM) is a by-product in the alumina manufacturing process, which is generated in large quantities. The challenge of increasing RM reserves poses a threat to the environment and can be addressed by its utilization in the construction industry. This study presents a comprehensive review of RM's effect on the various properties of cementitious and noncementitious materials to understand the feasibility of employing it to produce sustainable construction materials. The various studies reviewed suggest that RM could successfully be incorporated in concrete, mortar, bricks, and ceramic materials and can be used as a potential replacement for different property-enhancing admixtures. Besides that, the use of RM combined with other industrial by-products could further enhance efficient resource consumption. The article addresses the incorporation of RM as a partial replacement of cement, fly ash, and filler materials, appraising its influence on the fresh, hardened, durability, and radiological properties of the materials. The results revealed that RM with high pozzolanic activity could be used at low replacement levels to enhance the mechanical properties of the other materials. However, RM usage could improve the durability properties even for higher replacement levels. Considering the strength and environmental performance, conservatively RM can be around 50% as fly ash replacement and 12.5% as cement replacement in concrete mixes. It can be used at 40% as fly ash replacement and 20% as cement replacement for mortar mixes. Since RM's characteristic properties vary significantly based on its source, the extent of its incorporation must be decided based on the required application and properties for effective usage. Utilization of RM in the construction, as mentioned, can address waste reduction, one of the primary aspects of the aluminum industry's cleaner production.