The Study On Measuring Concrete Permeability With Liquid-gas Method

For concrete structure in the practical engineering, the non-mechanics damages, such as alkali-aggregate reaction, sulfate attack, carbonization, steel rust, freeze and thaw, and so on, are unavoidable due to the exist of erosive media. The deterioration form of mono or multi-factor influences on the concrete property of construction and durability greatly, and shortens the service life of the concrete to a large extent. Permeability of concrete is the most important factor for these non-mechanics damages, so the permeability test of concrete is the normal and required item to study the durability of concrete.Now many scholar most and often choose the Quick Cl- permeability test (ASTM C 1202) method to study the permeability of concrete. But the results of these two methods deviate unavoidably from the actual data due to the polarization, generating heat, the chemical composition of the pore solution, and so on during the process of the test. At the same time, some scholars consider that there is no direct relativity between the electricity and the chloride migration, as well between ASTM C 1202 and Electric conductivity. And the traditional immersion method and GBJ82-85 are applied less due to the long test period, heavy and lower efficiency respectively. The liquid-gas method is improved based on the above methods, overcoming the defects of GBJ82-85. Using the liquid-gas method, permeability condition of concrete can be tested and indicated quickly, efficiently, and the influences on concrete of alkali-aggregate reaction, sulfate attack, carbonization, steel rust, freeze and thaw can be inflected indirectly. It is significant on the research and monitor on the durability of concrete.In the experiment design, comparison samples are modeled, cured and tested at one time for reducing deviation, and w/c are choosed from 0.6 to 0.26, test pressure frome 0 to 4MPa for covering test area. The conductivity of concrete is tested during the permeability to describe permeability process in detail.The main technique route of this study is that by the methods of liquid-gas method, GBJ82-85 and ASTMC1202, concrete and mortar permeability are tested at one time. The method correlates with GBJ82-85 very well, and the relative coefficient is 0.9728-0.9913. The method can replace of GBJ82-85.On the other hand, through inhibted performances of concrete and mortar, the permeability refutations with different w/c, ages, admixture, and physics chemistry absorb regulation of different viscosity permeable liquid, the liquid-gas method isproved science and accuracy. Because adopting with liquid-gas method it case clearer concrete permeability regulation. Different concretes relativity is more exact and more efficiency and fixed quantity.