JAUE2024-060: Characterization of Modified Biomass Fly Ash on Deformation and Microstructure of Cement Mortar

Abstract

With a global focus on sustainable development, innovation in building materials is essential. Conventional cement production emits large amounts of CO2, necessitating environmentally friendly alternatives. Biomass fly ash (BFA), produced from biomass waste, can partially replace cement, enhancing concrete's workability and long-term performance. This study used JIS Class II fly ash (J ash), and wood biomass fly ash (M, N, and O ash) as admixtures, modified via a 30-minute flotation beneficiation method. With a W/B ratio of 0.5, fly ash addition rates were 0%, 15%, and 30%. Mortar flow, compressive strength, and drying shrinkage were measured. Field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS) analyzed the morphology and composition of hydration products. Results showed that modifying woody biomass ash with flotation was counterproductive. A 30% fly ash replacement rate effectively controlled drying shrinkage, while a 15% rate achieved higher early compressive strength. However, the 30% demonstrated higher compressive strength growth from 29 to 91 days. Despite lower fluidity, O ash exhibited compressive strength and dry shrinkage values comparable to JIS Class II, making it the most applicable woody biomass ash in this study. This research supports BFA's potential as an eco-friendly cement alternative.