Glued-laminated bamboo with different adhesive options for a more sustainable construction

This is the authors' abstract. We don't add key points for this paper.

Despite the growing demand for sustainable construction materials, limited research has evaluated the performance of bio-based adhesives, such as castor-oil-based polyurethane (PU), compared with conventional polyvinyl acetate (PVA) in glued-laminated bamboo (GLB) for structural use. This study assessed the physical, mechanical, and microstructural properties of GLB bonded with PU and PVA. PU-bonded samples showed higher mechanical performance (18% improved modulus of rupture and 37% improved shear strength); however, these differences were not statistically significant (p > 0.05). In terms of moisture-related properties, PVA exhibited higher water absorption (72% vs. 65%) and slightly lower thickness swelling (9.1% vs. 9.9%) after 168 h of immersion, indicating comparable dimensional stability between the two adhesives. Scanning electron microscopy (SEM) and image analysis confirmed PU’s deeper penetration and stronger inter-fiber cohesion, whereas PVA showed limited penetration and more interfacial failure. These findings indicate that PU is more suitable for load-bearing applications, while PVA is more appropriate for non-structural uses, emphasizing the critical role of adhesive penetration in GLB structural integrity.