Charring Behaviour of Cross Laminated Timber (CLT) Members: Effects of Fire Retardant Treatment

Engineers and architects worldwide express an ever-increasing interest in using CLT in construction, which is hindered by the combustible nature of timber. An effective way of addressing this issue is by treating the CLT element with a Fire Retardant (FR). In this work, the charring rate of non-treated and FR-treated CLT specimens is compared. The experimental investigation employed 150 mm × 100 mm × 65 mm spruce CLT specimens that were exposed, in a vertical position, to a constant 75 kW/m2 radiative heat flux, using a porous burner. Based on the temperature profiles, the mass loss, the heat release rate and the charring rate measurements, the improvement of the FR-treatment on the overall fire behavior of the CLT elements was quantified. In addition, four different charring rate correlations were validated against the obtained experimental data, aiming to determine their relevant prediction accuracy.