Effective utilization of agricultural ashes in development of sustainable geopolymer concrete

The use of concrete is widespread in the construction industry due to its successful and desirable properties. As industrial and urban development rapidly increases, the demand for concrete is also reaching new heights compared to other materials. In this regard, there is a pressing need for alternative materials to replace cement and industrial by-products. This paper proposes the effective utilization of agricultural ashes, including rice husk ash (RHA), bagasse ash (BA), and palm oil ash (PA), in geopolymer concrete. The study evaluates fly ash-based geopolymer concrete's compressive strength and microstructural performance by replacing fly ash with varying percentages of agricultural ashes. The results show that including agricultural ashes in the fly ash-based geopolymer blends yields higher strength than the 100% fly ash-based geopolymer concrete. However, using higher dosages of agricultural ashes decreases strength and forms micro-cracks in the geopolymer phases. Therefore, using 20% RHA or 15% BA or 15% PA as a precursor in fly ash-based geopolymer concrete can produce sustainable construction material and contribute to greener construction. Green concrete can help advance the circular economy and promote environmental protection.