Intermediate-Scale Laboratory Method to Qualify Heat-Delaminating Adhesives for Use in Cross-Laminated Timber

The goal of this research was to develop a simple laboratory test for examining heat delamination in cross-laminated timber (CLT) panels. The laboratory test was designed to mimic the fire tests described in Annex B of the ANSI/APA PRG-320 standard, which is required for CLT product qualification in North America. The Annex B test requires a full-sized room (2.4 by 4.9 by 2.7 m) to be constructed and exposed to a design fire scenario. In this article, we scaled the mechanical and fire loads so that they could be conducted in an intermediate-scale furnace with 1.1 m2 of exposed CLT panels. The mechanical loads were scaled to match the bending moment prescribed in the standard. The fire loads were scaled by matching the temperature profiles when an inert furnace lid was run and then matching the gas flow on all subsequent tests. Panels made from adhesives that passed the Annex B test passed the laboratory-scale test; panels that failed the Annex B test failed the laboratory test with the exception of one replicate. Correlations were found not only for CLT but also for a veneer-based mass timber panel. Measured temperature profiles within the furnace were similar to those measured near the compartment ceiling in the Annex B test. The scaled-down test in this article can be used to screen which adhesives are likely to pass the full-scale Annex B test.