Characterization of local 2:1 clays for utilization in limestone calcined clay cements

As calcined clays are gaining prominence as supplementary cementitious materials (SCM), demand for kaolinite-based 1:1 clay has surged, especially for Limestone Calcined Clay Cements (LC3). However, the potential of readily available 2:1 clay remains underexplored. Clays vary in composition, microstructure, and reactivity, with most becoming viable SCMs when activated. This study characterizes three local 2:1 clays in India against pure kaolinite to assess their suitability for LC3. Clays were characterized based on geotechnical properties, XRD and thermogravimetric analysis. Based on the TGA analysis, the dehydroxylation temperature for each clay was ascertained and calcined accordingly. The reactivity of the calcined clays was assessed by the Strength Activity Index (SAI). The blended cements with local 2:1 clays seemed to gain strength with an increase in age despite the poor early-age strength.