Hydration kinetics and mechanisms of carbonates from stone wastes in ternary blends with calcined clay

Abstract

This study aims to evaluate the feasibility of utilizing marble stone dust and Kota stone dust as carbonate source in the ternary cement blends with calcined clay. In this article, a novel application of these dusts in a system where they contribute to strength development through a chemical reaction is presented. Ternary cement blends were prepared with by replacing 45% of the ordinary portland cement by a combination of calcined clay and stone dust waste. Three stone dust wastes were collected from Rajasthan region in western India for this study. Crushed quartz and laboratory grade calcite were used as a substitute for stone dust wastes to produce control blends. The hydration process of the ternary cement blends with stone dust waste were studied using X-ray diffraction, thermogravimetric analysis and isothermal calorimetry. The mechanical properties were studied by measuring compressive strength at 1, 3, 7, 28 and 90 days. It was found that marble dust and Kota stone dust can be used as a carbonate source in ternary cement blends containing calcined clay, with formation of carboaluminate phases observed during the hydration of the cement. Formation of additional AFm phases such as stratlingite was observed in the absence of carbonate sources. The synergetic effect that exists in the OPC – calcined clay – limestone systems was also found to exist in the OPC – calcined clay – stone dust system, which led to improved compressive strength.