Study of electrical double layer effect on chloride transport in unsaturated concrete

• The EDL effect is more significant in the saturated concrete than the unsaturated one.
• The chloride concentration is increased only when the sign of zeta potential is negative.
• In the considered concretes, slag develops an EDL effect more than fly ash.

In this paper, a physical model of chloride ingress concretes is proposed. The originality of the model lies in its consideration of electrical double layer (EDL) phenomenon in unsaturated concrete. The EDL is occurring at the interface between pore walls and pore solution. The work is performed by solving the multispecies ionic transport equations coupled with those of humidity. To show the effect of slag and fly ash, several concretes were considered. The chloride profile was simulated. The results show that chloride concentration increase for EDL negative more than EDL positive. The EDL effect is reduced in unsaturated concrete due to discontinuity of liquid phase. Finally, it is also shown that the concrete containing slag develops and EDL more important than those manufactured with fly ash.