Influence of Clay Mineral Composites and Calcined Temperatures on the Rheological Properties of LC3 Mortar

Limestone calcined clay cement (LC3) is a promising low-carbon alternative to traditional cement, capable of reducing clinker content and CO2 emissions while maintaining comparable performance. However, the role of clay mineral composites in calcined clay, particularly their types and calcination behavior, remains underexplored. In this study, clay mineral composites were mixed with metakaolin in fixed proportions and calcined at different temperatures to systematically investigate their influence on the rheological and hydration properties of LC3 mortars. The results reveal that clay mineral composites calcined with metakaolin at 800°C exhibited optimal rheological performance, with montmorillonite achieving the highest shear stress (790 Pa), significantly outperforming chlorite (527 Pa) under the same conditions. Montmorillonite and illite demonstrated superior hydration activity, accelerating cumulative heat release and enhancing hydration product formation. These findings underscore the critical role of clay mineral composites types and calcination conditions in tailoring LC3 formulations, providing practical insights for developing sustainable and high-performance cementitious materials.