This study is to investigate the effect of wood preservative on the mechanical properties of glulam timbers made from low density Malaysian hardwood timbers. Utilization of lower density Malaysian tropical timber for structural applications have not exploited extensively due to their inferior strength. By converting into treated glued laminated (glulam) timbers it could offer the possibility of this timber as competitive structural materials. Nevertheless, wood preservative has been known to interfere with mechanical properties and strength performance of wood. Therefore, to achieve the objective of the study 5-ply of glulam beams with 100mm(w)x 150mm(t) x3000(l)mm dimension were manufactured using sawn timber treated with wood preservative copper chrome arsenate (CCA)(Tanalith). Timber species from low density timber with strength Group (SG) 5, Bintangor (Calophyllum spp) and SG 7, Sesendok (Endospremum spp) were selected for this study. All glulam beams were fabricated in accordance with MS 758:2001. 3-point bending test was conducted based on ASTM D198-84 (ASTM 1987a) to determine the modulus of elasticity (MOE) and modulus of rupture (MOR) of treated glulam timbers. Shear test was also been conducted in order to understand the effect of adhesive bonds and performance on CCA (Tanalith) treated glulam timber. The experimental work also included untreated timber of the same species used as control. Results showed that treated glulam for both of Sesendok samples had the highest MOE and MOR values of 66106N/mm2 and 123N/mm2 respectively. Correspondingly, for untreated control samples were indicated lowest MOE and MOR values of 51036N/mm2 and 112.28N/mm2. Bintangor had indicated the highest MOE and MOR values of 53546N/mm2 and 119.66N/mm2. Overall properties of treated samples tested in work resulted in higher values compared to untreated samples. No significant different for MOE values for both treated Bintangor glulam and Sesendok glulam. All specimens were reached 100% wood failures with more than 10N/mm2 of shear strength. From the results of this study, it can be concluded that by preservative treatment it could upgrade the performance of low density timbers as structural materials.

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