Transient Chloride Ion Diffusion in a Homogeneous Concrete Column

Abstract

The current investigation presents a numerical simulation based on the finite difference method of the unsteady, two-dimensional diffusion process of chloride ion through a concrete column having a rectangular cross section. A time-dependent surface chloride concentration has been applied to the four boundaries of the subject column. Chloride ion concentration profiles have been presented assuming a time-dependent diffusion coefficient of chloride ion into concrete. Both, the time dependence of the surface chloride ion concentration and the diffusion coefficient have been based on previously published empirical equations. The proposed mathematical model was based on the conservation of species equation along with Fick’s law of diffusion. The time before the onset of the chloride-induced corrosion has been discussed in relation to geometrical and operating conditions of the present problem. It has been concluded that chloride-induced corrosion attacks reinforcement steel bars located at the corners of the column cross section significantly sooner than it attacks other bars located farther away from corners.