Study of the chloride transport in unsaturated concrete: Highlighting of electrical double layer, temperature and hysteresis effects

In this paper, we suggest a modelling of chloride ingress in unsaturated concretes. The originality of our model lies in its consideration of the electrical double layer (EDL), the temperature as well as the isotherm sorption-desorption hysteresis. In order to consider slag and fly ash effects, several concretes were considered and experimentally tested in tidal conditions. The chloride profile was simulated by a multispecies model. The simulations show that the chloride concentration increases with a negative EDL more than with a positive EDL and that this effect occurs mainly in the concrete containing slag where the overlapping is more important due to the pore size distribution. We also show that both temperature and hysteresis affect the chloride ingress at the surface more than in deeper layers of the concrete specimen most likely due to a drying effect. Finally, the results put forward a good agreement between measured and simulated chloride profiles mainly when the hysteresis is taken into account.