Effect of biomass ashes on the strength, durability and microstructure of cement mortars

As the cement industry shifts towards low carbonisation, this study examines the impact of biomass ash on the compressive strength, flexural strength, water absorption and resistance to chloride ion penetration of mortar, specifically using corn stalk ash (CSA), biomass power plant ash (PPA) and grey rice husk ash (GRHA). The results indicate that the optimal activation of CSA occurs with calcination at 500°C for 6 h, followed by rapid cooling in ice water, significantly improving the microstructure and early strength of the mortar. Incorporating 5% CSA increases compressive strength and reduces the mortar’s chloride diffusion coefficient by 8.6%. Adding 15% GRHA enhances the mortar’s water absorption and resistance to chloride ion penetration, reducing the chloride diffusion coefficient by 21.3%, while PPA significantly decreases water absorption. Biomass ash enhances the overall performance of mortar through its filling effect, internal curing and pozzolanic activity. This study provides a reference for the use of biomass ash in cement-based materials.