Bonding performance of cross-laminated timber-bamboo composites

Bamboo is one of the most important renewable resources in China, leading to the development of bamboo products as well. Alternative applications of bamboo need to be developed in the field of construction, especially in cross-laminated timber (CLT) construction, due to better mechanical performance of bamboo and the increasing popularity of CLT construction in recent years. The bonding performance of cross-laminated timber-bamboo (CLTB) composites fabricated with Spruce-pine-fir (SPF) dimension lumber and bamboo scrimber boards was investigated here. L9 (34) orthogonal experiments with four factors (adhesive type, adhesive spreading rate, clamping pressure, and clamping time) and three levels were applied to evaluate their impacts on the bonding indicators of CLTB through block shear and delamination tests. Results showed that adhesive type had the most critical influence on the bonding performance. The optimal manufacturing parameters were adhesive of phenol resorcinol formaldehyde (PRF), adhesive spreading rate of 250 g/m2, clamping pressure of 1.0 MPa, and clamping time of 420 min, respectively. PRF adhesive yielded higher block shear strength, wood failure percentage, and lower rate of delamination than one-component polyurethane (PUR) and emulsion polymer isocyanate (EPI), especially under wet or boiling condition.