Harnessing Agricultural Residues for Eco-Efficient Cement Substitution in Mortar: A Pathway to Low-Carbon and Sustainable Construction

Several studies have explored the use of agricultural waste materials in construction. Using these materials in building not only eliminates them but also prevents environmental contamination. The purpose of this study is to evaluate the impact of rice husk ash (RHA) as a partial replacement of cement. An assessment was conducted to determine the compressive strength, flexural strength, porosity, water absorption, and density of the hardened samples. Furthermore, the microstructures and chemical compositions of several samples were analyzed using SEM and XRD analysis. The replacement levels of rice husk ash were 0%, 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. From the findings, it was observed that the possible utilization of RHA was up to 20 percent. The water absorption, porosity, and dry density of RHA mixed mortar samples were observed to increase with the percentage addition of RHA. This is due to the greater number of voids in RHA compared to cement. However, it decreases as curing age increases. XRD and SEM analysis matched the macro-property analysis and helped explain the positive effect of RHA. The linear regression between flexural strength and compressive strength was found to be fcr = 0.1146 fck + 1.0882, with an R² value of 0.9602. The statistical analysis using a dendrogram revealed three distinct cluster formations for the different variables.