Study on the chloride diffusion coefficient calculated from a simple accelerated chloride penetration test using electricity

There are many reports on the durability of concrete structures affected by chloride-induced reinforcement corrosion in Japan. The penetration speed for chloride damage is evaluated using the chloride diffusion coefficient, which varies depending on mix proportion, cement type and admixture type. In general, the diffusion coefficient has been given as a function of the water-cement ratio or by experiment. An immersion experiment is usually carried out by soaking a specimen in salt water, but this method requires a long immersion period. On the other hand, electrophoresis examination can be carried out in a short period of time, but as this method is performed in the steady state the results may differ from the actual phenomenon. In this research, an evaluation method is proposed for the unsteady state by inducing chloride ion movement with electricity. This method calculates the diffusion coefficient in the unsteady state by measuring the penetration depth of the chloride ions up to the time when electricity supply was stopped, and various cement types were examined such as normal (N), early strength (H), low heat (L), blast-furnace slag cement type A (BA), type B (BB), type C (BC) and fly-ash cement type B (FB). Not only could the diffusion coefficient be calculated from the chloride ion depth, but this calculation could be carried out for periods as short as 24 hours. The variation in diffusion coefficient by cement type was also verified. Overall, it is believed that this method can calculated the chloride ion coefficient in the unsteady state in a short period of time.