Research into Coal Gangue-Based Cementitious Materials: A Review

Coal gangue (CG), a bulk solid waste produced during coal mining, is rich in active components such as silicon and aluminum oxides, making it a high-quality raw material for the production of cementitious materials. Its utilization represents a significant pathway for achieving high-value applications of CG and facilitating the low-carbon transformation of the cement industry. Owing to advantages such as low carbon emissions, environmental friendliness, cost-effectiveness, and tunable performance, CG-based cementitious materials have been extensively investigated by researchers worldwide. Studies have focused on various aspects, including cementitious backfill materials, CG solid waste-based cement, geopolymers, concrete, and composite materials derived from CG. This paper systematically reviews the regional distribution, mineral composition, chemical constituents, and reactivity characteristics of CG. It further summarizes recent advances in activation techniques, performance optimization, and engineering applications of CG-based cementitious materials. Current challenges, such as insufficient activation efficiency, ambiguous hydration mechanisms, and limitations in large-scale application, are critically analyzed. Finally, future research directions and development trends are outlined to provide a theoretical foundation for further investigation and industrial implementation of CG-based cementitious materials.