| As the development of new high efficiency additives and the application of superfine mineral admixture, the water needed for concrete is reducing and concrete is more and more density, at the same time, microstructure and chemical composition of concrete change greatly too. Impermeability of concrete is improved significantly, so the traditional test method to evaluate impermeability of concrete is inapplicable. Researchers all over the world have been seeking new method for it, but there is no one receiving acceptance. Because of this condition, applicability of water permeating method to evaluate impermeability of concrete is studied in this paper.Permeability of concrete and its correlation with chloride ion diffusion coefficient under different test conditions including water pressure method and tension method are studied. Soakage of concrete and penetration length at different water pressure and pressure maintaining time are tested, and the results show that soakage at a water pressure is not linear relation with time. Water soaking rate of concrete is reducing with time, and soaking mainly happens within original one hour and increases slowly in subsequent 6 hours. Penetration length is linear relation with pressure approximately. Water pressure method can distinguish permeability of concrete with different strength or air content, and penetration length or permeability coefficient has good correlation with chloride ion diffusion coefficient. Tension method also can distinguish permeability of different concrete, but it has discreteness compared with water pressure method. Permeability coefficient tested by tension method is about 10 times of that by pressure method, which indicates that water can permeate into concrete easily under tension.Water pressure method is applicable for evaluating permeability of concrete. The test time needed is short, and operation and pretreatment is easy. It is an effective method for quick testing and evaluating permeability of concrete.
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