Tri-dimensional modelling of cementitious materials permeability from polymodal pore size distribution obtained by mercury intrusion porosimetry tests

An analytical model is developed to predict permeability of cement-based materials. It is based on the geometrical modelling of a porous structure as a tri-dimensional cubic pore network, which contains an association of n types of pores with radii R_i and lengths l_i. This geometrical configuration gives the model the ability to be applied to all types of pore size distribution. The permeability is expressed in function of porosity, tortuosity, critical pore radius and constrictivity, which depends on pore size distribution. These parameters are obtained from mercury intrusion porosimetry measurements. The predicted permeability values were compared with experimental ones obtained by direct measurements according to Darcy's law. The experimental validation concerns three mortars chosen for their polymodal pore size distribution. Theoretical and experimental results are in the same order of magnitude. However, the model could be improved by a better estimation of the material morphological parameters. This would be possible by using further investigation methods, in addition to mercury intrusion porosimetry tests.