A State-of-the-Art Review of Limestone Calcined Clay Cement (LC3): Mechanisms, Performance and Sustainable Applications

Reducing carbon emissions in the cement industry is vital for global carbon neutrality. Limestone calcined clay cement (LC3) has emerged as a promising low-carbon binder because it can lower the clinker fraction while using widely available clay and limestone resources. Although LC3 research has expanded rapidly, large-scale implementation is still constrained by variability in raw-material quality, incomplete understanding of coupled reaction mechanisms, rheological challenges, and scattered engineering evidence. This work presents a structured critical review of LC3 raw materials, hydration and microstructure, fresh-state behavior, mechanical performance, durability, solid-waste utilization, engineering applications, and environmental performance. The available evidence shows that the commonly studied LC3-50 formulation can reduce the clinker fraction to approximately 50 wt% while maintaining competitive engineering performance when raw-material reactivity, sulfate balance, mixture proportioning, and curing are appropriately controlled. Low-grade clays can also be viable after suitable activation and formulation adjustment. Carbonation resistance and admixture compatibility remain important challenges that require application-specific evaluation. By emphasizing evidence traceability and the conditions under which reported benefits are obtained, this review supports more reliable LC3 design and industrial implementation.