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 (LMC 2 -MM) in comparison to limestone calcined clay cement containing either calcined muscovite-rich mixed clay (LC 3 -CM) or metakaolin (LC 3 -MK). Results from pozzolanic activity tests (R 3 and modified Chapelle) revealed a significant improvement in the reactivity of muscovite-rich mixed clay via mechanical activation (MM) compared to thermal activation (CM). LMC 2 -MM exhibited similar structure and properties to conventional LC 3 -MK, and the enhanced reactivity of MM over CM led to improved properties for LMC 2 -MM compared to LC 3 -CM. The hydration of LMC 2 -MM was superior to that of LC 3 -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 LC 3 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. • Mechanically activated muscovitic clay (MM) exhibited high pozzolanic activity. • Mechanical activation outperforms calcination, enhancing 2:1 clay performance. • MM enhanced early hydration and strength in LC 3 through accelerated reaction. • Mechanical activation broadens the types of clay suitable for LC 3 production.