Mechanical activation of muscovite-rich clay: A novel approach for ternary blended cement

Clay minerals with a 2:1 structure typically exhibit limited pozzolanic activity after calcination, which constrains their use as supplementary cementitious materials. Mechanical activation has emerged as a promising approach to enhance the reactivity of clays, potentially improving the performance of cement containing mixed clays rich in 2:1 clay minerals. This research assesses the properties of ternary blended cement produced with mechanically activated muscovite-rich mixed clay (LMC²-MM) in comparison to limestone calcined clay cement containing either calcined muscovite-rich mixed clay (LC³-CM) or metakaolin (LC³-MK). Results from pozzolanic activity tests (R³ and modified Chapelle) revealed a significant improvement in the reactivity of muscovite-rich mixed clay via mechanical activation (MM) compared to thermal activation (CM). LMC²-MM exhibited similar structure and properties to conventional LC³-MK, and the enhanced reactivity of MM over CM led to improved properties for LMC²-MM compared to LC³-CM. The hydration of LMC²-MM was superior to that of LC³-CM, achieving significantly refined porosity at both 3 and 28 days. This study presents a novel approach to ternary blended cement by incorporating mechanically activated mixed clay. It demonstrates that mechanical activation enhances the properties of blended cement, particularly at early ages when using muscovite-rich clays, achieving compressive strength comparable to conventional LC³ with metakaolin. The mechanical activation of muscovite-rich mixed clay presents a promising strategy for using local clay resources in regions where kaolinite-rich clay is scarce.