Study of durability and the physico-mechanical properties of thermally modified wood

Heat-treated wood is a credible alternative for certain kinds of tropical timber. It is also an alternative for certain polluting wood preservatives. This study aims to determine the changes in physico-mechanical properties and durability of wood that is subjected to heat treatment. For this, we studied five species (oak, ash, natural beech and a variant known as steamed beech, poplar, Douglas-fir). For each species, we had fifteen reference samples and fifteen corresponding treated samples. The results show a decrease in the hygroscopicity and an increase in dimensional stability of heat-treated wood in relation to the degradation of hemicelluloses. The mechanical properties are influence variously, because heat-treated wood is stiffer but also more brittle. The modulus of elasticity increases slightly after treatment. Side hardness and compressive fracture of heat-treated wood may increase up to 30%. On the other hand, the modulus of rupture, the ability to slit and impact may decrease by 50%, 60% and 70%. The durability of heat-treated wood against wood-destroying fungi increases. However, within each species, the durability increase varies greatly. Additional tests conducted to understand this variability, suggests that the heat distribution is not homogeneous within the processing unit. Moreover, our work suggests that durability is related to the fixed carbon content and that this path would be interesting to explore in the future.Bois traité thermiquemen