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Experimental Study of Fire-Induced-Delamination of Cross Laminated Timber



Daniel Brandon, Birgit Ostman, Joseph Su, Amanda Kimball, Matthew S. Hoehler


Cross Laminated Timber (CLT) is increasingly used as a structural material for tall buildings, due to its structural properties and low carbon footprint. CLT is a mass timber product, which is made by crosswise gluing layers of timber lamellae. Recent architectural trends include having visible CLT surfaces, which, in the event of a fire, can become involved in the fire and act as fuel to the fire. A study by the Fire Protection Research Foundation (FPRF; USA), National Fire Protection Agency (NFPA; USA), National Research Council Canada (NRC-CNRC; Canada), Research Institutes of Sweden (RISE; Sweden) and National Institute of Standards and Technology (NIST; USA) has focused on the contribution of exposed CLT to compartment fires. The study included a review of previous compartment fire tests, full-scale fire tests of compartments with and without exposed CLT structures, the development of design methods for engineers and intermediate scale fire tests to identify high-temperature resistant adhesives for CLT. The full-scale compartment tests showed the undesirable consequences of CLT delamination during a fire (i.e. fall-off of exposed lamellas), which occurred due to weakening of the CLT adhesive. These consequences included fire regrowth after a period of decay or a continuation of a fully developed fire. This can make self-extinction of a compartment fire not possible, implicating that the fire will lead to collapse if the fire is not manually extinguished or extinguished by sprinklers. In order to achieve self-extinction of flaming combustion in compartments with exposed CLT it is important to avoid fire-induced delamination. It was shown that fire-induced-delamination can be avoided using high-temperature-resistant adhesives. A test method was developed to identify adhesives that are not prone to fire-induced-delamination under relevant fire conditions. A summary of the test methodology, evaluation and results is discussed in this article.
SFPE Europe


CLT, cross laminated timber, furnace test, fire, delamination
Created January 1, 2019, Updated January 29, 2019