In order to figure out the influence of cover thickness and chloride content at the
rebar on chloride induced corrosion in marine RC structures, seven existing dolphins
which were constructed in Tokyo bay and have been in service for more than 26
years were investigated. In addition, the laboratory test was carried out by using a
large number of RC specimens with varied chloride content in concrete, cover
thickness, water-cement ratio of concrete and type of cement, to examine the chloride threshold value for the initiation of steel corrosion and the influence of chloride content at the rebar on corrosion rate.
As the results, it can be found that the chloride threshold value is more than
2.0kg/m3 and the corrosion rate of rebar increases drastically when chloride content at the rebar exceeded more than 4.0kg/m3.