Optimization of rice husk ash-based alkali activated composites (AAC) blended with bauxite and GGBS for sustainable building materials
Kalyan Kumar Moulick, Amit Shiuly, Soumya Bhattacharjya, Debasis Sau
Abstract
Rice husk ash (RHA)-based Alkali Activated Composites (AAC) offer a sustainable alternative to traditional construction materials, promoting both agricultural waste management and environmental responsibility. Thus, in the present study an effort was made to prepare RHA based AAC blended with Bauxite and GGBS through experimental and optimisation procedure. For this purpose, several numbers of RHA based Ground Granulated Blast Furnace Slag (GGBS) AAC were prepared by incorporating different percentage of Bauxite, GGBS, Alkali Activators and water in the laboratory and compressive strengths were evaluated. Based on the experimental data, regression equations were proposed of compressive strength as a function of RHA, Bauxite, GGBS, Alkali Activators and water. In addition to that, using the regression analyses, optimization of test results was conducted. Furthermore, experimental validation was conducted for optimized mix. The optimized mix proportions per cubic meter for oven-cured AAC were 750 kg of RHA, 1100 kg of bauxite, 150 kg of GGBS, and 230 kg of water, while for ambient-cured AAC, the proportions were 945.3 kg of RHA, 889.08 kg of bauxite, 165.6 kg of GGBS, and 306.6 kg of water. The optimized RHA-based Alkali Activated Composites (AAC) demonstrated compressive strengths ranging from 18 to 24 MPa, with the highest strengths achieved at the specific bauxite and GGBS ratios. Further, the microstructure of the optimized samples was conducted by performing the Scanning Electron Microscope, Energy Dispersive X-ray and X-Ray Diffraction on the broken samples. The result revealed critical microstructural features such as gel phases and partial crystallinity, contributing to the material’s strength and durability. The current findings indicate that RHA-based blended AAC can serve as an effective solution for environmentally friendly, economically sustainable construction materials, demonstrating commendable performance within the construction industry.