CIB-W18/38-18-1 INTERNATIONAL COUNCIL FOR RESEARCH AND INNOVATION IN BUILDING AND CONSTRUCTION WORKING COMMISSION W18- TIMBER STRUCTURES ADHESIVE PERFORMANCE AT ELEVATED TEMPERATURES FOR ENGINEERED WOOD PRODUCTS

Engineered wood products, such as I-joists and laminated veneer lumber (LVL), have traditionally been manufactured with phenolic-based adhesives in North America. In the last few years, however, an unprecedented number of non-phenolic-based adhesive systems, such as polyurethane-based and isocynate-based adhesives, have been introduced to the engineered wood products industry. While these relatively new adhesives have demonstrated their compliance with most international adhesive standards, concerns have been raised by the fire services and others on the performance of these adhesives at an elevated temperature, such as just below the ignition temperature of wood. It is recognized that full-scale fire assembly tests, such as ASTM E119, CAN/ULC S101, or ISO 834, address the fire performance of wood assemblies. However, it is arguable that the adhesive, as a critical component of glued engineered wood products, needs to be evaluated to ensure that the adhesive will not degrade below the wood substrates being adhered when exposed to extreme heat prior to wood ignition. Unfortunately, no international adhesive standards exist in testing the adhesive to such an elevated temperature. A task committee, as chaired by the first author, was formed in June 2004 by the engineered products industry in North America to address this issue with input from key adhesive suppliers to the industry. Through coordinated efforts, an industry standard was developed and adopted by the engineered wood products industry in March 2005. Test data suggests that this standard can be used to screen out those adhesives that significantly lose adhesive bond strength at the temperature near the wood ignition temperature. Thi