MODELING OF CHLORIDE MIGRATION IN CONCRETE

In many cases, reinforced concrete structures are influenced by penetration of deteriorating salts that cause corrosion of the steel reinforcement. From a micro-structural point of view, concrete is a heterogeneous composite with tortuous pore microstructure with partially or fully saturated pores. Water in pores allows salt ions to be dissolved and transported towards reinforcement. Different mechanisms such as diffusion or convection take place. The ion convection can be caused by electromotive force acting on charged particles and is caused by an electrical potential gradient. This contribution is devoted to modeling of the dffusion-convection problem applied to chloride migration in concrete. The influence of an external electric field is studied and problems of chloride penetration and extraction are solved. It is shown in the paper that the electric field accelerates the chloride migration by multiple times compared to natural diffusion and can be used as an efficient treatment for rehabilitation of reinforced concrete structures affected by chloride attack.