A finite-element model is developed for the heat and mass transfer process in refractory concrete. Using this model, simulations are carried out for drying of refractory concrete slabs heated on one side only to investigate the effects of an impermeable surface, which may be either the heated face or the unheated face, on pore steam pressure and moisture removal rate. Simulation results indicate that the presence of an impermeable surface produces a very significant rise of pore steam pressure which may result in explosive spalling of the concrete.