Wood ash-based materials with improved post-fire resistance for building and infrastructure applications

Alkali-Activated Materials (AAMs) are gaining attention because of different advantages such as CO₂ emissions reduction and improved fire-resistance. Wood Ashes (WA), potentially derived from fires, can been proposed as secondary raw material in AAMs manufacturing to guarantee a double positive impact: improved fire resistance of construction materials and secondary raw material valorisation. In this paper WA-based alkali activated composites were studied in terms of mechanical behaviour and fire-resistance properties compared to traditional cement-based systems. AAMs composites were prepared starting from two industrial by-products, FA and GGBS, replacing them with different percentage of wood ashes. Thermal resistance of the optimal mixtures, in terms of mechanical strength, were also evaluated. WA-based AAMs showed better fire performance, with lower compressive strength loss and a higher average residual compressive strength. LCA results suggest that utilizing wood ashes, especially when locally sourced, enhances environmental performance by partially substituting more environmentally harmful aluminosilicate precursors.