Effect of solute parameters on wick action in concrete

Abstract

Models are presented that describe chloride transport in concrete from a face in contact with salt solution to a drying face. The models are in two parts: (1) location of an internal liquid/gas interface, and (2) characterisation of the transient chloride diffusion and dispersion process in the concrete. A detailed analysis of the effects of chloride on the interface location and quantity of water vapour leaving the dry face of the concrete is undertaken. The principal effect is the reduced vapour pressure of the solution which is shown to have a significant effect on the location of the interface when the concentration of the solution at the wet face of the concrete is low and the relative humidity of air at the dry face is high. The magnitude of this effect is investigated by imposing a limit on the solubility of chloride at the interface, at which point chloride precipitation would occur. Predictions of the models are compared with experimental data, a numerical solution, and an asymptotic solution and good agreement is obtained.