Reactivity of montmorillonite clays of various grades as supplementary cementitious materials: a comparative assessment

The discovery of the feasibility of using activated clays to produce reactive aluminosilicates has significantly expanded the raw material base for supplementary cementitious materials, opening up new prospects and options for low-carbon cements. Furthermore, the potential of kaolin clays for producing pozzolans has been thoroughly studied and practically realized. However, the more widely available and accessible non-kaolin clays of the 2:1 structural type require further comprehensive studies of their suitability in relation to the variety of influencing factors. In this study, the reactivity of five montmorillonite clays calcined at 830 °C and milled to Dv,50 of 11.5–13.8 µm was explored through chemical, mechanical, and thermal methods. Based on the consistency of results obtained through these techniques insights into the relationship between the reactivity of low-, medium, and high-grade montmorillonite clays and their chemical/mineralogical composition are presented. These findings advance the understanding of the categorization of montmorillonite clays as supplementary cementitious materials.