In a deeply carbonated concrete deck under field exposure at the coast, chloride profiles in a carbonated layer were complex, and its diffusivity seemed to be markedly different from that in a noncar-bonated layer. This paper discusses what the profiles mean. First, the study attempted to determine both apparent diffusion coeffi-cients of chloride ions in the noncarbonated and carbonated layers by fitting. Then, the fast ion transfer in the carbonated layer was recognized. In addition, it was found that the complex chloride profiles cannot be well expressed by the theoretical or numerical solutions for a composite medium consisting of the layers as far as the surface chloride content is assumed to be constant. Subse-quently, the influence of a seasonal variation in the surface chlo-ride content upon the profile was examined. The results show that the complex chloride profiles should happen due to the high diffu-sivity in the carbonated layer under the variable surface chloride content, suggesting that the chloride ions run out from the carbon-ated surface easier. |