In Architectural Institute of Japan, design technique of concrete used for reinforced concrete structure subject to exogenous type salt attack is provided. It is desired that required penetration resistance of chloride ion to concrete is decided based on the actual environment at that design technique. However, it is difficult that preparation of technical data is not enough in current condition. It is one of those reasons that an accelerated test method of chloride ion penetration is not established. Accordingly, the past researchers conducted the experiment with original test methods of various conditions. Therefore, this paper presents the results of the accelerated tests and the exposure tests on the penetration and diffusion property of chloride ion in concrete from literature survey. Literatures are selected by some requirements, accordingly accelerated test reports are 18 and exposure test reports in coastal area are 7. These accelerated test reports were classified into alternating immersion and immersing in salt water.
In general, it is said that penetration and diffusion properties of chloride ion in concrete follow the diffusion equation. Moreover, this equation is prescribed by two characteristic values which are chloride ion content of concrete surface and diffusion coefficient. At the results of arrangement and examination of literatures data, the characteristic values showed the tendency to change with passing period, and then converge to the constant value at the exposure test. At the accelerated test, immersing in salt water showed that characteristic values change similar with exposure test. Moreover, these tendencies can be expressed with model formulas. At alternating immersion of accelerate test, however, characteristic values were constant from initial stage of test. Furthermore, influences of water cement ratio on characteristic values were little in each test method.
Relationship of diffusion coefficient with water cement ratio is shown in each specification of Architectural Institute of Japan and Japan Society of Civil Engineers as the relation expressions. In these expressions, diffusion coefficient increases with water cement ratio, and the same tendency was shown in the each test method from this examination. And then, diffusion coefficients of exposure test were distributed near these expressions. At the accelerated test, on the other hand, diffusion coefficients were distributed approximately 10 times of exposure test at the same water cement ratio. Nevertheless, difference of diffusion coefficient by water cement ratio was exceedingly smaller than the dispersion of experimental values.
In the accelerated test, the method of immersing in salt water is the most simple and showed similar tendency with the exposure test in this examination. Accordingly, in this paper, the studies were conducted under the test conditions of the immersing in salt water of accelerated test, to estimate the penetration and diffusion properties of chloride ion in concrete. Consequently, chloride ion content of concrete surface was influenced by NaCl concentration of salt water immersed, however diffusion coefficient was not influenced by it. Moreover, there is little difference of characteristic values between the test results of 182 days and those of 365 days, and the test term of 182 days was shown as the safe side for the estimation of durability.
