Estimation of moisture superficial diffusivity in porous materials

In the work different types of diffusion which proceed in capillary-porous media were presented. First the theoretical expressions were talked over which described a dependence between superficial and volumetric moisture diffusion and temperature. Next one discussed the idea of effective moisture diffusion coefficient taking into account both analysed mechanisms of water vapour diffusion in volumetric part of material pores and diffusion in moisture films adsorbed on pore walls. On that basis one introduced a relation coupling the effective moisture diffusivity with volumetric and superficial diffusion coefficients. Finally one presented the results of own experimental research of effective moisture diffusivity-temperature dependence and sorption isotherms for building gypsum samples what allowed estimating the superficial diffusivity of gypsum.