Strip-Like Laminations Influence on Bending and Bonding Performance of Yellow Birch Glulam

Strip-like laminations are wood lamellae formed by face-gluing small wood segments to reduce the effect of natural defects and enable the use of lower-grade timber. This technique offers a promising solution for transforming low-grade wood into solid products. However, its impact on full-scale structural components such as glulam beams has yet to be thoroughly assessed. This study investigated how external layers made of strip-like laminations affected glulam’s bending properties and bonding performance. Grade No. 2 yellow birch (Betula alleghaniensis Britt.) was bonded with one-component polyurethane to fabricate six-layer glulam beams, with strip-like laminations placed on the outer layers. Mechanical testing, including four-point bending, block shear, and delamination, was conducted in accordance with North American standards. Results showed a one-third reduction in the variability of modulus of rupture (MOR), while maintaining comparable performance to traditional glulam configurations. Although apparent modulus of elasticity (MOEapp) was slightly lower and similar to beams containing visual defects, block-shear strength exceeded 90% approval. Some cases of delamination above 10% highlight opportunities for process refinement. These findings demonstrate the potential of strip-like laminations for improving material utilization and provide valuable insights for optimizing manufacturing strategies.