Chloride ingress in concrete as measured by field exposure tests in the atmospheric, tidal and submerged zones of a tropical marine environment

Abstract

Five grades of concrete were exposed in the atmosphere, tidal and submerged zones of a tropical marine environment for times up to 80 weeks and the chloride ion ingress profiles determined. The measured chloride profiles were compared with profiles calculated on the basis of diffusion theory and the agreement was found to be reasonably good for all 3 zones. Diffusion coefficients, D, for the chloride ion calculated from the measured ingress profiles agreed well with previous data from laboratory tests and from surveys of marine structures. D was found to be mainly dependent on the water/cement (W/C) ratio and changed little with the addition of superplasticizers. The use of data for the diffusion coefficient, D, and equilibrium surface chloride level, Ce, obtained from the chloride ingress profiles, to the calculation of the time-to-initiation for corrosion of the steel reinforcement is briefly discussed. © 1993.