The purpose of this study is to establish the performance-based evaluation method for the durability of concrete structures under marine environments. The target deteriorations are both the chloride induced corrosion (chloride attack) and the concrete deterioration due to seawater (sulfate attack).
　For the performance-based evaluation method for ‘chloride attack’ , there are three important parameters; a critical chloride concentration for initiation of steel corrosion (Clim), a chloride ion concentration at the concrete surface (C0) and an apparent diffusion coefficient (Dap). In this study, they were investigated based on site survey and long term exposure tests. For Clim, 2.0 kg/m3 is proposed in port reinforced concrete structures, based on long term exposure test in the pool which tidal conditions were simulated. For C0, it is proposed that C0 is varied linearly with the distance between H.W.L. and concrete surface. For Dap, it is proposed that characteristic value of diffusion coefficient is obtained by multiplying the estimation equation of ‘JSCE standard specification for concrete structures’ by 0.65 in case of normal portland cement.
　For the performance-based evaluation method for ‘sulfate attack’ in the concrete structures under marine environment, the method is not established. In order to propose the estimation method for the deterioration of concrete under marine environments, both concrete cores sampled from existing structures and test specimens exposed in the outdoor pool of natural seawater were examined for various tests both from the mechanical and chemical points of view. From these results, a simple estimation method for the concrete deterioration under marine environments is proposed.