Feasibility study on the preparation of ternary cement with calcined slag powder and seashell powder as supplementary cementitious materials

Abstract

Producing limestone calcined clay cement (LC3) can reduce cement use and CO2 emissions, but the availability and quality of clay and limestone pose challenges. This paper explores substituting these materials with seashell powder and engineering spoils for their high CaCO3 content and cohesive clay. This study introduces the concept of shell powder-calcined slag cement (SCSC) and compares its properties with traditional limestone powder-calcined slag cement (LCSC). Results indicated that the 3d compressive strength of seashell powder calcined slag cement reached 29.19 MPa at 15% supplementary cementitious materials (SCM) dosage, which was 4.7% higher than that of limestone powder calcined slag cement at 27.87 MPa, and the 7d strength was 12.1% higher, which was attributed to the fact that calcium carbonate in seashell powder existed in a more active form. The addition of shell powder enhances the formation of calcium-rich compounds, leading to an optimized mineral phase composition in the ternary cement. Importantly, shell powder's impact on the heat of hydration, pore structure, and mechanical properties matches or surpasses that of limestone powder. Therefore, shell powder proves to be a viable substitute for limestone in ternary cement preparation.