AGEING RESISTANCE OF PRESERVATIVE-TREATED CROSS-LAMINATED TIMBER UNDER HIGH HUMIDITY ENVIRONMENTAL CONDITION

Engineered wood products are globally recognized for their low carbon footprint and are increasingly utilized in environmentally conscious construction. Traditionally, formaldehyde-based adhesives have been the preferred choice in the formation of strong durable bonds in more extreme service classes. The structural performance of one-component polyurethane (1C-PUR) adhesives in the engineered wood industry has continuously developed since the 1990s, and their utilization has expanded due to their ease of use. While there is much evidence with reliable data for, the durability of adhesive bonding using 1C-PUR with different wood species, very limited work has been undertaken on the durability of 1C-PUR when bonding preservative-treated softwood. In this study, the bonding of cross-laminated timber was assessed. Two commercially available 1C-PURs were subjected to experimental ageing and a comparison with a resorcinol formaldehyde (RF) adhesive was conducted. A series of Mode I fracture energy tests using the single-end notched beam test configuration was carried out on crossbonded specimens, which examined the use of two different preservative treatments and also untreated Radiata pine grown which was grown in New Zealand. The tests were conducted using artificially accelerated ageing subject to high humidity and temperature at three-month intervals for up to a period of six months. Favourable wood failures were achieved in the unaged and aged investigations to date for all combinations. No noticeable chemical changes in the adhesive layer were recorded by examination using Fourier Transform Infrared Spectroscopy (FTIR) in the ageing regime to date.