DETERMINING A REPRESENTATIVE RANDOM PORE-NETWORK FOR MOISTURE SORPTION AND MIGRATION IN CEMENT MORTAR

The pore-structure of cement mortar is modelled by a cubic network of pores in order to simulate various static and dynamic phenomena concerning moisture, using elements of the theory of percolation. The pore diameter distribution is fitted in order to obtain a simulation of the hysteretic sorption in good agreement with experimental data. In the range of large diameters, the distribution is more accurately defined with the help of mercury intrusion data. The isothermal moisture migration in the structure previously determined is modelled, taking into account both vapour diffusion and viscous flow of liquid water, and assuming local equilibrium. Even at large liquid water content of the material, the vapour diffusion is found to be the dominant migration mechanism. The simulated coefficient of transfer is in very good agreement with the drying experimental data. The model is not as successful in the description of imbibition experiments. Some explanations are proposed.