Glulam beam made from hydrothermally treated poplar wood with reduced moisture induced stresses

• Published in: Construction & building materials Vol. 135; pp. 386 - 393
• Main Authors: Mirzaei, Ghaneh, Mohebby, Behbood, Ebrahimi, Ghanbar
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-03-2017; Elsevier B.V
• Subjects: Analysis; Bending strength; Glued laminated timbers; Glulam; Hydrothermal treatment; Mechanical properties; Moisture induced stress; Poplar; Stiffness; Stresses (Materials); Thermal properties; Iran; Bending strength; Glulam; Poplar; Stiffness; Hydrothermal treatment; Moisture induced stress
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2016.12.178

•Hydrothermally modified wood could be used for engineered wood products; such as glulam beams.•Application of modified wood could reduce moisture induced stress and moisture gradients in glulam beams.•Moisture induced stresses are correlated with wood moisture contents in glulam beams.
Moisture induced stresses were studied in glulam beams, which were made from hydrothermally treated poplar (Populus deltoides) wood in the current research work to understand whether the hydrothermal wood modification can reduce those stresses or not. Wood blocks with dimensions of 6 (R)×10 (T)×73 (L)cm3 were cut and hydrothermally treated in a stainless steel reactor at temperatures of 140 and 160°C for a holding time of 30min. The treated wood blocks were dried to achieve moisture content of 12%. Afterwards, the glulam beams (4-ply) were manufactured by using polyurethane (PUR) adhesive. In order to evaluate cross sectional moisture induced stresses (MISes) and bending properties of glulam beams; wood density, equilibrium moisture content (EMC) of wood, 4-point bending of the glulam beams (according to ASTM D 198-02), 3-point bending of the treated and untreated wood (according to ASTM D 143-09) and the moisture induced stresses in cross section of the glulam beams were determined. The results showed that the hydrothermal treatment reduced the cross sectional moisture induced stresses as well as relevant moisture gradients and also it caused increase of the bending strength as well as stiffness of the treated wood and the glulam beams.