Assessment of the unsaturated water transport properties of an old concrete: Determination of the pore-interaction factor

In this study all the data needed to describe water transport (drying) within an existing concrete structure were characterized using a simple drying experiment. The properties (desorption isotherm, porosity and the unsaturated water transport properties namely, diffusivity and permeability) were evaluated by post-processing the weight loss data. Once obtained, the permeability evolution was used to check the validity of the Mualem–van Genuchten equations. It appeared that the default pore-interaction factor value proposed by Mualem (p = + 0.5) is just a rough estimate: the values obtained in this study were all negative. Comparing these values to the literature, the pore-interaction factor seems to be correlated to the van Genuchten's exponent m.