Development of Protection Technique for Wood-Based Structural Members with Poly-Vinyl Alcohol Fiber Sheet (I)

摘要

To prevent the degradation of structural glued laminated timbers (glulams) exposed to outdoor conditions, we investigated the reinforcement of those surfaces with poly vinyl alcohol fiber sheets (PVA-S). First, we studied the bonding of PVA-S on a wood surface with epoxy resin adhesive, including an examination of compatibility among wood preservatives (ACQ, AAC, NZN, NCU, CUAZ2), PVA-S and adhesive resin. Next, we studied the waterproof properties of PVA-S, the decrease of dimension changes and prevention of cracks or delaminations in reinforced glulam. We also investigated the influence of PVA-S reinforcement on the distribution of glulam moisture content via an outdoor exposure test. High bonding durability was obtained for wood-PVA-S adhesion, regardless of the pressing method, and the adhesion of preservatives-treated wood and PVA-S provided adequate bonding durability. Water did not penetrate below the surface of glulams with PVA-S lamination. Reinforcement with PVA-S decreased dimension changes of glulams and prevented the occurrence of delaminations or cracks during cyclic wet-dry treatment. PVA-S reinforcement prevented an increase of moisture content in glulams exposed to outdoor conditions.