Ground wood ash as a supplementary cementitious material: Effects on strength, durability and environmental performance of concrete

This study investigates the use of wood ash (WA3 and WA4), both unground and ground for 10 and 20 min, as a partial replacement for Portland cement in concrete. Fly ash (FA) is used as a reference. The effects of incorporating ground and unground wood ash on fresh and hardened properties, hydration behavior, microstructure, durability, and environmental performance were evaluated. Grinding wood ash significantly improved the compressive strength of concrete and increased the cumulative heat release during hydration. Air-entraining admixtures significantly improved the freeze-thaw resistance of concrete with ground wood ash and reduced surface scaling compared to unground ash. Furthermore, grinding reduced the mobility of key heavy metals, enhancing environmental compatibility. Overall, 10-minute grinding provided the optimal balance between performance and environmental safety. These results support the controlled use of ground wood ash as a sustainable supplementary cementitious material in concrete, contributing to both concrete performance and environmental benefits.