A MODEL OF HEAT AND MASS TRANSFER IN CONCRETE DURING FIRE

Abstract

A model of heat and mass transfer in concrete during fire was presented. The model takes into account the 1) conduction of heat, 2) filtration of gas in the pore, 3) diffusion of water vapor and adsorbed (liquid) water through the pore, 4) desorption of adsorbed water and 5) decomposition of water of crystallization. The rates of desorption of physically adsorbed water and of decomposition of water of crystallization were explicitly expressed. The calculated results of temperature, pore pressure and water contents were compared with experiments on cement mortar walls. As to the temperature, the agreement was very good, including the phenomenon of creeping of temperature. As to the water content and pore pressure, the agreement was not perfect quantitatively but good qualitatively. Therefore it can be said that the model is valid to predict the temperature changes of concrete members during fire.