Sustainable geopolymer footpath block using kaolin mining waste as fine aggregate with bagasse fly ash and coal fly ash as precursor

Abstract

This study aims to develop environmentally friendly footpath blocks by utilizing Kaolin Mining Waste (KMW) as a fine aggregate and fly ash (FA)/bagasse fly ash (BFA) blends as a precursor in the geopolymerization process. These materials, considered industrial by-products, offer the potential for reuse, reducing the reliance on natural resources while promoting sustainability. The experimental works involved substituting FA with BFA at varying proportions by binder weight to identify the optimal ratio for producing footpath blocks that meet standard mechanical requirements. The mechanical characteristics of the footpath blocks were evaluated by testing compressive and flexural strengths, and water absorption. The results indicated that replacing 10 % of FA with BFA (FA90BFA10) accomplished the maximum 28-day compressive strength of 15.6 MPa. A KMW/P ratio of 1.0 proved most effective in increasing flexural strength and minimizing water absorption. Microstructural analysis revealed that combining BFA substitution and the optimal KMW/P ratio created a dense geopolymer matrix with low porosity, enhancing the material's strength and durability. This research demonstrates that integrating KMW, FA, and BFA effectively produces footpath blocks with mechanical properties that meet the local industry standard. Incorporating these agricultural and coal-combustion by-products reduces industrial waste while fostering the manufacture of sustainable footpath block which supports long-term resource conservation.