A novel short-term immersion test to determine the chloride ion diffusion coefficient of cementitious materials

•This study proposes a new method to determine the chloride ion diffusion coefficient.•The diffusivity is calculated from the concentration change in a source solution.•The concentration change in the source solution is employed as a boundary condition.•A series of tests was performed to validate the proposed method.•The proposed method can estimate the diffusion coefficient within two weeks.

The chloride ion diffusion coefficient is a crucial factor in the durability of concrete structures exposed to seawater. A number of test methods have been developed to determine the chloride ion diffusion coefficient of concrete. Most of these test methods require an excessive test duration or represent a chloride ion penetration mechanism that applied an electrical potential to accelerate chloride ion penetration. This study proposes a new test method to determine the chloride ion diffusion coefficient while avoiding these deficiencies. The proposed method incorporates a new analytical approach that calculates the diffusion coefficient from the change in chloride ion concentration in a source solution. The proposed method can be called a short-term immersion test in comparison with traditional long-term immersion tests. The short-term immersion test was validated by comparison with a long-term immersion test and an electrical migration–diffusion test. It was found that the proposed test method and analytical solution can estimate the chloride ion diffusion coefficient within two weeks.