Influence of Heat Treatment on the Static Bending Strength of Spruce Wood

Abstract

The goal of this investigation was to find out influence of heat treatment at low temperatures on the Lithuanian spruce wood bending strength. The influence of heating temperature and duration on the strength of spruce wood during statical bending has been investigated. The tests were carried out using samples with size of 20 ´ 20 mm in cross-section and 300 mm in length. Density of samples varied from 460 up to 500 kg/m³. The samples were heated at conditions close to those used during manufacturing process. Temperature was equal to T = 60, 80, 100 and 120 °C and heating duration was selected t = 24, 48, 72 and 96hours. The obtained results reveal that heating at relatively low temperatures, influences the strength of the spruce wood during bending. After the increase of both drying temperature and duration decrease of bending strength was found. The longer heating duration at lower temperatures results in less strength changes compare to those heated at higher temperatures for shorter duration. It was found that heating temperature is more significant technological parameter for spruce wood bending strength compare to those of heating duration.