Abstract

Leading economies are moving towards a bio-based economy for sustainability, but Africa struggles to utilize its bio- resource such as timber for advanced engineering application due to its natural limitations. Nevertheless, glue lamination (glulam) is promising for enhancing wood for structural application. Hence, this study investigated the shear strength of glue laminated (glulam) joints of Albizia zygia (A. zygia) timber species bonded with polyurethane (PUR) adhesive and other essential physical and mechanical properties in line with relevant standards. Briefly state the methodology before results to ensure flow. The results showed that the mean density of the wood species is 519 at a mean moisture content of 12%. The wood recorded a mean volumetric shrinkage and volumetric swelling of 1.17% and 6.52% respectively. Other properties include mean bending strength at 53.89 , mean stiffness at 6106 N/mm2, compressive strength parallel to grain at 32.70 and mean tensile strength at 33.61 . Furthermore, the lap shear strength for glue laminated joints was tested according to EN 302-2013 standard and compared to control solid beams. The mean shear strength for glulam was 2.32 while it was 1.64 for the control beams. Thus, the glued joints performed better in shear than the control specimen. Finally, the residual shear strength of the joints was a mean value of 1.28 after subjecting them to accelerated aging tests (AAT). This is equivalent to 44.83% decrease of the shear strength in the dry use state. Hence, glue laminated A. zygia using PUR is not suitable for external use due to weathering effects on its shear strength. Based on the findings in this study, A. zygia is a moderately dense wood suitable for structural use but for interior application when laminated with PUR. It is shown that locally sourced A. zygia can be enhanced through glue lamination for structural joints in service class 2 according to Eurocode 5.