Thermodynamic Modeling of Cementitious Paste Containing Sugarcane Bagasse Ash and Rice Husk Ash

Supplementary cementitious materials (SCMs) are widely used to promote sustainable construction methods. It consists of industrial and agricultural by-products, viz. fly ash, blast furnace slag, rice husk ash (RHA), sugar cane bagasse ash (SBA), etc. The chemical composition, fineness, number of reactive phases, the content of the pore solution, etc., affect the reaction process of SCM and it is difficult to understand the effect of these parameters on the hydration process. Models are being created to understand the effect of these parameters. Thermodynamic modeling (TDM) is a useful tool for understanding the composition of hydrated cement, the effects of SCM on hydration, predicting the composition of pore solution, etc., of cement and SCM. In the present work, two types of ordinary Portland cement OPC-1 and OPC-2 with varying chemical and mineral compositions are investigated with two SCMs (SBA and RHA). The impact of the cement content on the hydrates generated in binary mixes with SBA and RHA is studied using TDM. The CEMDATA database is utilized with the GEMS3K software. It was observed that OPC-1 and OPC-2 hydration models predicted CSH gel, ettringite, hydrotalcite, calcite, and Portlandite. In addition to these products, mono-carbonate was also observed in OPC-2. In comparison to OPC-1, OPC-2 predicts 19% more CSH gel and 26% less hydrogarnet. In the case of binary mix using RHA in increased amounts, jennite-kind CSH transforms into tobermorite-kind CSH, and in the case of SBA blended systems, a decrease in Portlandite was observed. The results obtained from TDM are further validated using experimental data obtained from the literature. It can be concluded that TDM highlights the type and amount of hydrates that develop in the hydration process of cement and its blends.