Block Shear Bonding Performance of Laran Glued Laminated Timber under Simulated Environmental Conditions

Abstract

The block shear bonding performance was studied for glued laminated timber (glulam) manufactured from laran, a Malaysian plantation hardwood, under four treatment conditions designed to simulate service environments. Forty block shear specimens were tested to determine shear strength and wood failure percentage (WFP). The conditions comprised (a) dry (control, equilibrium laboratory climate), (b) water-soak (immersion in 20 ± 3 °C water for 24 h), (c) boiling Immersion (100 °C for 6 h followed by cooling), and (d) boil–dry–boil cycle (repeated hot–wet and drying exposure). Each specimen (50 × 50 × 50 mm³) was loaded in shear using a universal testing machine. Results revealed a progressive reduction in both shear strength and WFP with increasing treatment severity. Dry samples exhibited the highest bonding performance, while specimens subjected to the Boil–Dry–Boil Cycle showed the greatest deterioration. These findings demonstrate the sensitivity of laran glulam to moisture and thermal cycling, provide baseline data for adhesive bond durability across service classes, and offer valuable insights for improving treatment strategies, product design, and the long-term structural reliability of glulam in tropical construction contexts.