Condensation and isothermal water transfer in cement mortar Part I — Pore size distribution,equilibrium water condensation and imbibition

The pore size distribution of cement mortar is studied in relation to water sorption experiments with the help of mercury intrusion and nitrogen sorption. The importance of adsorbed water is pointed out. Isothermal imbibition experiments at four temperatures are presented. The temperature-dependence of the mass transfer coefficients is compared to the one predicted by the classical model. Significant discrepancies are noticed. On the basis of the knowledge of the pore structure, a modelisation of the transfer process at moderate water content is proposed. It particularly takes into account Knudsen's vapor diffusion and effects of the presence of a discontinuous capillary phase interacting with vapor diffusion.