Struvite Mineralized Wood as Sustainable Building Material: Mechanical and Combustion Behavior

A more extensive use of wood can reduce the environmental and climatic impacts of the building industry. However, flammability limits the application of wood in multistory and high rise timber buildings. Struvite mineralization has been shown to be a green solution for fire-resistant timber, but the influence of struvite minerals on the mechanical and gluing properties of wood as well as the combustion behavior have not been studied yet. In this work, we investigate the mechanical properties of mineralized wood by compression, bending, and tension tests as well as gluing properties by tensile shear tests. Evolved gas analysis using GC/MS system is applied to determine the thermal decomposition behavior of the mineralized wood, and Double shot analysis reveals volatile components of mineralized wood during the thermal decomposition process. The results show that the struvite mineralization treatment is a bulk modification technique that improves the fire resistance of wood. The mineralization can significantly influence the thermal decomposition behavior of wood, which results in an enhanced char formation. This char layer is a fire barrier that slows down the heat and oxygen penetration. The heat penetration rate of wood panels fabricated with mineralized wood is 0.6 mm/min during the cone calorimeter test, which is half of that of the wood panels fabricated with native wood. Transverse strength and stiffness under compression were improved, whereas mechanical loading in the longitudinal direction revealed similar or decreased strength and stiffness. The mineralization had a minor impact on the gluing properties of solid wood. Wood mineralization by struvite may enable the more extensive use of wood in the construction sector as a substitute for less eco-friendly building materials.