Measurement of char oxidation rate of glue laminated timber of Japanese cedar and larch under forced air flow

Abstract

Char oxidation during the post-fire cooling period, which generates substantial heat is one of the important factors in achieving the self-extinguishment required for wooden structural members in high-rise or large-scale buildings. Here, the char oxidation rates of Japanese cedar glue laminated timber were measured at various heating intensities using a cone calorimeter. The critical conditions for stopping of char oxidation were a heating intensity of 6.0 kW/m2 and surface temperature of 250.0 °C, indicating that Japanese cedar continues to char oxidation at lower temperatures than larch. An equation relating the mass loss rate to the surface temperature of larch was developed for Japanese cedar. The effect of a forced airflow over the surface of the specimen on the char oxidation was also investigated. When a forced airflow of 1.1 m/s was applied to specimen surface, the mass loss rate increased compared with that without a forced airflow; however, the surface temperatures were similar to or slightly greater than those without a forced airflow.