The chloride penetration model, which considers diffusion and sorption, is proposed. The FEM program developed on the basis of the diffusion and sorption model estimates chloride concentration variation according to cyclic humidity and temperature. In the model of chloride ion penetration, the chloride ion diffusion and sorption analysis are conducted on the basis of the pre-estimated relative humidity data in each element. Each element has different analysis variables at different ages and locations. The large difference of relative humidity between inner and outer concretes causes the chloride ion penetration by sorption. But the difference reduced by the humidity diffusion makes the effect of sorption on the chloride ion penetration decrease. The cyclic humidity in situation increases the effect of sorption on the chloride ion penetration and the chloride ion concentration by the model considering the movement of chloride ion by moisture diffusion is much larger than that by the model not considering the mechanism. Therefore, the in situ analysis of chloride ion penetration for harbor concrete structures needs to consider the cyclic humidity condition and the long-term sorption mechanism.
A major source of durability problems in marine and harbor concrete structures is the corrosion of steel by the ingress of chloride ions. The chloride-induced corrosion of steel bars causes the spalling of concrete cover and the loss of steel cross-sectional area. As a result, safety and serviceability of marine concrete structures are jeopardized. In order to prevent steels from being corroded, it is necessary to estimate the chloride ion penetration in concrete structure with age and location. But the time and space dependent properties of concrete make the analysis of chloride ion penetration difficult. Also, the changeable environmental conditions such as relative humidity and temperature increase the complexity of the analysis of the chloride ion movement.
