Akademik Veri Yönetim Sistemi
4th International Civil Engineering & Architecture Conference, Trabzon, Türkiye, 15 - 17 Mayıs 2025, ss.1-10, (Tam Metin Bildiri)
One of the most efficient routes to decarbonising the cement industry is using supplementary cementitious materials to substitute Portland cement partially. Raw clays are the most abundant materials in the field and have promising pozzolanic properties. However, non-clay materials' impurities, such as calcite, dolomite, quartz, and feldspar, may influence their reactivity. Thus, this paper systematically explores, for the first time, the influence of calcite impurities on the physicochemical and pozzolanic properties of alternatively activated (MCA) 2:1 (montmorillonite) clays and their potential utilisation in the LC3 system. Montmorillonite samples before or after MCA were blended with 35% calcite, equivalent to the optimum ratio (2:1 clay-to-calcite) for the LC3 system. The results suggest that adding mechanochemical-activated montmorillonite significantly improved the compressive strength, showing superior or similar properties to their thermally activated counterpart in the LC3 system. In particular, simply co-milling montmorillonite with calcite results in the best performance by achieving approximately 15% higher strength than its thermally activated counterpart. The superior strength of co-milled montmorillonite can be related to increasing MCA efficiency with calcite addition due to its shielding effect, where the harder component (limestone 3 Mohn hardness), compared with montmorillonite (1.5 Mohn hardness), stays coarser and abrades the softer one. It was also observed that a decrease in the crystallinity of calcite after MCA can be another reason for better performance.