A review on the utilization of red mud in concrete: Effects on fresh, mechanical, and durability properties

The increasing accumulation of bauxite residue, commonly known as red mud (RM), presents significant environmental challenges due to its high alkalinity and limited reuse. Utilizing RM as a supplementary cementitious material in concrete offers a promising route for waste valorization and reduction of cement-related environmental impacts. This review synthesizes current research on the effects of RM incorporation on the fresh, mechanical, and durability properties of concrete. RM incorporation generally reduces workability owing to its fine particle size, angularity, and high alkalinity, resulting in increased water and superplasticizer demand, particularly when RM replacement exceeds approximately 15%. Mechanical performance is frequently enhanced at low to moderate RM replacement levels approximately 5–20% due to micro-filling effects and limited pozzolanic activity, while higher dosages tend to reduce strength. Durability-related properties, including water absorption and chloride ion penetration, show improvement at RM replacement levels up to approximately 15% because of pore refinement and microstructural densification, whereas sulphate resistance may deteriorate at higher replacement levels. From a sustainability perspective, the utilization of RM in concrete presents a viable pathway for industrial waste valorization and reduction of cement-related environmental impacts.