WATER-VAPOR ADSORPTION AND TRANSFER IN CEMENT-BASED MATERIALS - A NETWORK SIMULATION

In this paper, we develop a discrete approach to describe the transport of condensable vapours through microporous substances such as cement-based materials. We consider only isothermal water migration under uniform atmospheric air pressure, at temperatures lower than 100-degrees-C with negligible gravity. The pore structure which is supposed to be representative of the material is built on a two-dimensional random network of tubes. The basic phenomena (adsorption-desorption, diffusion, condensation) that occur during water vapour transport in a single cylindrical pore under steady-state conditions are taken into account. We emphasize that capillary condensation can be expected to cause vapour flow amplification of several orders of magnitude. This phenomenon provides us with a possible explanation of some experimental results.