Exploring the potential of calcined montmorillonite-kaolinite clay with medium percentage of clay minerals for low-carbon cements

Expanding the raw material base and diversifying supplementary cementitious materials based on distribution, availability, and competitiveness with traditional materials is a key focus for promoting the production and application of low-carbon cements. This approach is crucial for ensuring the sustainable development of the cement industry. Extensive research and practical experience in recent decades have highlighted the promising potential of using thermally activated clays to create low-emission cements. Calcined clays have now become significant and growing part of the range of reactive aluminosilicates suitable for use as primary or supplementary sources in producing clinker-free or low-clinker cements. This is facilitated by the abundant reserves of clay raw materials and the high reactivity of activated clays. The practical implementation of thermally activated clays followed extensive, long-term studies on the potential use of various types of clays. Research focused on the influence of chemical and mineralogical compositions, activation methods, and other factors on their reactivity. While important parameters for kaolin clays, such as kaolin content, optimal temperature and duration of thermal treatment, and fineness of grinding, are well-defined and included in standards, these aspects are not thoroughly studied for polymineral and montmorillonite clays. This study examines the impact of temperature and duration of calcination on the reactivity of montmorillonite-kaolinic clay with an average clay minerals content and explores its potential in environmentally-oriented low clinker cements.