Effects of Oxygen Concentration on the Reaction to Fire of Cross-Laminated Timber in a Controlled-Atmosphere Cone Calorimeter

This paper deals with the fire reaction as well as the gas and aerosol production of Cross-Laminated Timber (CLT) submitted to fire in oxygen-depleted environments. A Controlled-Atmosphere Cone Calorimeter (CACC) coupled to a Fourier Transform Infrared (FTIR) spectroscopy and an Electrical Low Pressure Impactor (ELPI) was used for this purpose. This combination enabled simultaneous assessments of Mass Loss Rate (MLR), evolved gases (qualitatively and quantitatively) and aerosols (size distribution and concentration) in the smoke. Several oxygen levels (21, 18, 15 and 10% O₂) were studied at an external heat flux of 50 and 20 kW/m². The combination of these two parameters allowed the response of CLT to be classified according to different fire scenarios. Indeed, an oxygen decrease shifted the combustion towards incompleteness or even prevented combustion. The production of carbon monoxide and methane was significantly promoted as well as acetaldehyde and ethene in some cases. The aerosol size distribution was slightly affected by oxygen depletion. Furthermore, decreasing the heat flux greatly reduced the decomposition rate but also promoted the production of unburnt gases.