Characteristic properties of thermally compressed oil palm wood and its potential for glued laminated timber products

Oil palm trunk biomass, abundant in tropical zones, can be utilized as raw materials for lumber-based products to serve the growing building industry; however, its relatively poor mechanical properties must be improved to meet structural requirements. This work aims to improve the properties of oil palm wood as a raw material for glued-laminated timber via thermal compression. Low-density (191–350 kg/m3) and medium-density (350–530 kg/m3) oil palm wood were thermally compressed at 200°C for 1 h with 40% and 25% target compression ratios, respectively. The thermally compressed oil palm experienced different degrees of compression throughout its thickness, which determined its density profile. Thermally compressed medium-density wood had a more uniform density, which makes it more favorable for structural usage allowing simpler connection design. Only the bending and tensile strengths in the parallel-to-grain direction of the thermally compressed medium-density wood met the requirements of a specific class of structural softwood timber. Block shear tests were performed to evaluate the feasibility of face-bonding the thermally compressed wood using a two-component polyurethane adhesive. All block shear test specimens had 100% wood failure percentages. Thus, the thermally compressed medium-density palm wood can be used for glued-laminated timber production under a condition where its own structural grade is established.