Creep behaviour of densified wood

Abstract

Due to the reproducibility, good workability, suitable mechanical properties, and attractive aesthetic appearance, timber is widely used in the building industry. Among those properties, mechanical properties are important for the useability of timber in construction applications. It is well known that there is a positive relationship between wood density and its mechanical properties. That means the thermo-hydro-mechanical (THM) densification, i.e. transverse compression of the wood cells only by using additional temperature, moisture and mechanical action to increase its density without structural fracturing is a practicable method to increase the performance of low-density species and thereby improve its mechanical properties. The previous studies on wood densification mainly focused on the influence of process parameters on wood physical and mechanical properties and how to use post-treatment to reduce the set recovery. This study is in the field of increasing the use of densified timber in construction applications and thereby strengthen the competitiveness of wood as a construction material. In construction, however, densified timber normally needs to be exposed to long-term loading which may lead to creep deformation and reduction of load-bearing capacity. There is an obvious risk of reduced serviceability and safety of constructions containing densified wood. Studies of creep characteristics of densified wood are rare, and therefore the purpose of this study was to fill the gap in knowledge if the field of densified under bending load. Scots pine specimens subjected to THM densification, THM densification with a post-heat treatment, and THM densification combined with phenol resin impregnation were loaded under 3-point bending under the 35% of maximum stress level at 20℃ and 65% RH. Results from these tests will be presented.Finansiär: Republic of Slovenia</p