A new model to calculate water permeability of cement-based materials from MIP results

In this article, we have established an analytical model of cement-based material permeability. The permeability is expressed in function of porosity, tortuosity, constrictivity factor and critical pore radius of the material. The modelling is based on the use of a tridimensional cubic pore network. Two types of measurements are carried out on mortars and cement paste: (a) mercury intrusion porosimetry (MIP) measurements so as to determine the model entry parameters which allow calculation of the ‘theoretical’ permeability; (b) direct water permeability measurements by the application of the Darcy's law so as to validate the model. The calculated and measured permeabilities are globally in the same order of magnitude. However, some differences are noted. They can be explained by the complexity of correctly estimating some model entry parameters (e.g. tortuosity). Moreover, the permeability expression established shows that it is more affected by tortuosity and critical pore radius variations than by porosity or constrictivity.