Char oxidation during the cooling period after a fire is one of the important factors in the self-extinguishment of a timber structural element because it involves a large amount of he at generation. In this study, the char oxidation rates of larch glue laminated timber were measured at various heating intensities, using a cone calorimeter. At a heating intensity of 12.4 kW/m
2, char oxidation continued with a mass loss rate of 2.41 × 10
-3 kg/m
2s and a surface temperature of 501.8°C. At a heating intensity of 8.4 kW/m
2, self-stopping of char oxidation occurred with a mass loss rate of 0.12 × 10
-3 kg/m
2s, which can be regarded as being close to zero. From all the measured values, it was concluded that the char oxidation ceases if the heating intensity is less than 8.4 kW/m
2 and if the surface temperature is less than 286.2°C. We also developed a formula to describe the relationship between the mass loss rate and the surface temperature during char oxidation, using an Arrhenius equation. The heat of combustion of the char layer was 23.41MJ/kg in average. Using the conditions and equations obtained from our measurements, it is possible to predict the behaviour of char oxidation in response to temperature of timber structural element. In the future, these values could be applied to a heat conduction calculation programme, which would make it possible to predict the self-stopping of char oxidation by calculation.
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