When concrete is intensely heated during fire, creeping of temperatures in the region of 100°C are often observed. To simulate this phenomenon, a simple mathematical model for heat and moisture transfer in concrete is presented. The model takes into account the conservation of heat, water vapor and liquid water. As to the water contained in concrete, reversible evaporation of adsorbed water in the pores and irreversible thermal decomposition of chemically adsorbed water in cement paste are considered. These equations are so-called stiff equations and rather difficult to solve. For numerical stability, they are formulated by using integral equations coupled with the diagonally implicit Runge-Butta method. Numerical solution of the model is compared with the experimental data.
Concrete, high temperature behavior, Mathematical modeling:, Modeling: simulation, Moisture transport, Runge-Kutta method, Species field, Structural materials, thermal conditions, Structures: thermal response, Temperature profiles, Water, adsorbed