Clays in transition: Addressing resource challenges and sustainable innovations in the construction sector

This review examines the reintegration of lower-grade clays into industrial applications, with a focus on ceramics, cementitious binders, and infrastructure materials as key sectors for sustainable transformation. It compiles current research and experimental insights to understand how such materials, often overlooked due to variable composition or limited reactivity, can be adapted to meet sector-specific performance requirements. In ceramic tile production, low-grade clays demonstrate varying degrees of sintering efficiency and thermal shrinkage, compared to traditional kaolin, offering viable paths for cost reduction. In cement applications, contrasts between kaolinite-based and limestone calcinated clay (LC³) reveal trade-offs in strength development, shrinkage behavior, durability, and CO₂ emissions. The review critically examines technical constraints, including mix variability, curing sensitivity, and activation thresholds, while emphasizing the need for regulatory adaptation and economic feasibility. In infrastructure applications, lower-grade clays have demonstrated promising adaptability for use in road base stabilization, where their plasticity and compaction behavior outweigh the demands for high purity. Their mineralogical variability influences moisture sensitivity and load-bearing performance, yet tailored mix designs and hybrid systems can mitigate these effects. The review underscores that while durability and regulatory compliance remain key challenges, these clays offer viable alternatives for low-carbon construction in regions with abundant local deposits. Through a synthesis of empirical findings and methodological analysis, this work contributes to the strategic valorization of underutilized clay sources and supports the advancement of resource-efficient material design.