The impact of moisture on salt treated and 2-step mineralized wood

A treatment to improve the reaction to fire of wood is the wood mineralization. Besides the reaction to fire of the mineralized wood, other mechanical and physical properties are less investigated. In this study, beech and oak were treated in a 2-step mineralization process to obtain calcium oxalate mineralized wood. The 2-step mineralization process is carried out by impregnating two salts diluted in water into the wood, consecutively. Two formulations were applied. For Formulation 1, potassium oxalate and calcium acetate and for Formulation 2 potassium oxalate and calcium chloride were used. Aim of the study is to investigate the impact of the treatments and in combination of the moisture on some selected properties of the mineralized wood. These properties are the swelling due to the mineralization treatment, the Brinell hardness and the volatile organic compounds emissions. The 2-step mineralization treatments increased the moisture adsorption of wood. However, the removal of unreacted precursors due to leaching provides a material with comparable moisture dynamics to untreated wood. Swelling, hardness and volatile organic compounds emissions are decreased by the mineralization. However, leaching of the reaction by-products leads to a material with comparable properties to those of untreated wood.