Enhancing wood fire resistance through magnesium-ion-induced calcium carbonate mineralization

Wood, as an abundant and sustainable material, is highly regarded for its aesthetic appeal and versatility, making it a popular choice for architectural and furniture applications. Nevertheless, its high flammability presents a major safety hazard, severely restricting its use in fire-prone settings. In this work, we focus on extending the time to ignition (TTI) of wood by increasing the delay between contact with an ignition source and the formation of an open flame, rather than merely reducing the heat release rate (HRR) and smoke release rate (SRR) during combustion. This study investigates how magnesium ions (Mg 2+ ) promote the mineralization of CaCO 3 within wood, leading to the formation of magnesium calcium carbonate (Mg-CaCO 3 ) and magnesium calcite . During wood combustion, Mg-CaCO 3 underwent dehydration and phase transformation, promoting the nucleation and growth of Mg-calcite within the wood matrix. This process markedly enhanced the wood's fire-retardant properties and compressive strength . Compared to untreated wood, the mineralized wood demonstrated a 53 s delay in TTI, a 68.8 % reduction in the maximum heat release rate (HRR), and a 101.7 % increase in compressive strength. The facile self-densification and heat-induced mineralization processes, combined with a water evaporation strategy, significantly enhance both the fire-retardant properties and mechanical strength , offering a promising approach for the development of fire-resistant, high-strength structural materials. Upon heating, Mg-CaCO 3 in the mineralized wood transforms into Mg-calcite, releasing water vapor and CO 2 , thereby enhancing the wood's fire-retardant properties. • Propose a novel mineralization strategy enhancing wood's strength, flame retardancy, and smoke suppression. • Highly flame-retardant wood prepared by regulating the crystal form of calcium carbonate using magnesium ions. • Magnesium ions are embedded in the calcium carbonate lattice, which causes phase change and dehydration, extending the TTI of wood.