Influence of Moisture Content on Chloride Diffusion in Concrete

Chloride penetration into the cover of reinforced concrete is often at the origin of early damage due to corrosion of the steel reinforcement. The penetration rate of chloride, however, depends strongly of the water content. If diffusion coefficients as measured on saturated concrete are used for the prediction of service life by means of Fick's second law, chloride penetration may be overestimated. The mobility of chloride in concrete in hygral equilibrium with different relative humidity of the surrounding air was determined experimentally. Chloride mobility in concrete, which is in equilibrium with 50 % RH, is very low. This has to be taken into consideration in realistic service life prediction. (A)