Exploring the Suitability of Fly Ash and Rice Husk Ash in One-Part Geopolymer: A Case Study for Sustainable, Low-Carbon Construction

The high carbon footprint and energy-intensive production processes associated with clinker-based cement necessitate developing sustainable and environmentally friendly alternatives urgently. This study focuses on the properties of a one-part geopolymer utilizing industrial and agricultural waste materials: Fly Ash (FA)and Rice Husk Ash (RHA). Fly ash was used as the primary aluminosilicate source, and rice husk ash was used as a silicate supplementary material. Solid NaOH was utilized as the alkaline activator. The physical and chemical properties of one-part geopolymer were changed with varying water-to-solid (W/S) ratios (i.e., $0.5,0.6,0.7$), Si/Al ratios (i.e., $2.5,3.0,3.5)$, and NaOH concentrations (i.e., $6 \mathrm{M}, 9 \mathrm{M}, 12 \mathrm{M}$), and they were systematically evaluated to optimize the mix design. Furthermore, microstructural and chemical bonding also depend on W/S, Si/Al, and NaOH concentrations, and the optimised geopolymer revealed well-developed bonding mechanisms and structural integrity. Furthermore, this experiment tested that One-Part Geopolymer (OPG) has lower embedded Carbon ($0.4 ~\text{kg} \text{CO}_{2}$), which is more than half of the embedded Carbon ($0.85 ~\text{kg} \text{CO}_{2}$ e) of Ordinary Portland Cement (OPC). It is an excellent sign for the sustainability of OPG over OPC. Therefore, this study underscores the suitability of coal power plant fly ash and industrial waste rice husk ash for synthesizing one-part geopolymers as a transformative solution for advancing environmentally sustainable construction practices that support the UN Sustainable Development Goals 9 and 12.