Intermediate Scale Fire Testing - A Practical Way To Screen New Adhesive Technologies​

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For nearly every engineered wood application to enter the market, wood adhesives need to be evaluated in a large-scale assembly such as the CSA O177 test for glulam or the PRG-320 Annex B test for cross laminated timber. These full-scale tests are costly and generally only performed when a company believes a new adhesive is likely to pass the test. A screening method to evaluate different technologies or hypotheses about how formulation changes may affect fire performance is needed. Many different small-scale tests exist for measuring the performance of a wood adhesive bond under elevated temperature (for example ASTM D7247). However, it is widely understood that these tests are not perfectly correlated with the full-scale tests needed to enter the marketplace. For the past 10 years, the Forest Products Laboratory has been developing intermediate-scale tests to examine the performance of wood adhesives in fire. These tests maintain the fire exposures specified in the full-scale tests but scale down the assemblies so that smaller specimens can be utilized, reducing costs and increasing the number of replicates that can be evaluated. Strong correlation between intermediate- and full-scale tests have been demonstrated for cross laminated timber, glue laminated timber, and wood I-joists. This presentation will summarize the intermediate-scale tests developed at the Forest Products Laboratory and give perspectives on other potential applications for intermediate-scale fire testing.