Ultrasound to determinate the modulus of elasticity of heat-treated woods subjected to field test

Abstract

This study aimed to evaluate the modulus of elasticity of heat-treated wood subjected to decaying in field environment, by employing the ultrasound technique. For this, wood of Eucalyptus grandis and Pinus taeda from a TWBrazil plantation were used. From each species were selected five trees, which were then unfolded in boards that were dried and heat-treated at the temperatures of 140 and 160 ºC. Afterwards, 75 specimens were obtained for each species, which were then exposed to the weather elements during 200 days and evaluated every 40 days, in the completely randomized design with a double factorial arrangement for the heat treatment and exposure time. In this period were collected data of the fungal decay potential in the site, and apparent specific gravity and dynamic modulus of elasticity (DMoE) from the wood samples. We verified the fungal decay potential increase with the exposure time, which also caused a reduction of the apparent specific gravity and DMoE in all treatments, for both species. E. grandis had a low stiffness loss while P. taeda had a higher loss with the increasing of exposure time, with significant differences of the species DMoE.