Research Of Influence Of Mineral Admixtures On Permeability Of Concrete

Permeability is one of the most important factors which influenced the durability of concrete. In this paper, compressive strength, chloride permeability of concrete with mineral admixtures were experimentally investigated. A experimental arrangement for testing gas permeability coefficient of concrete was designed and processed independently, and investigated the influence of gas pressure imposed on the concrete sample, gas flow rate, mineral admixtures and freeze-thaw cycle on gas permeability coefficient of concrete.Test results showed that increased water-cemenet ratio, compressive strength of concrete declined, the charge passed the concrete and chloride diffusion coefficient increased. The incorporation of fly ash can let compressive strength and chloride diffusion coefficient of concrete down, but the improvement of the charge is not very significant. When the mass percent of fly ash was 20%, the 60d charge and chloride diffusion coefficient of C30 concrete are bigger than the ones when the mass percent of fly ash was 10%, but they were lower than basic concrete. The incorporation of ground slag or silica fume can increase the 28d strength, and let the charge and chloride diffusion coefficient decline significantly.An experimental arrangement with data processing system for the test of the gas permeability coefficient of concrete was processed. The study shows gas pressure and flow influenced the test result of gas permeability coefficient clearly, the relationship between them and gas permeability coefficient is not simple proportional or inverse relationship. The incorporation of fly ash can let gas permeability coefficient of concrete down. When the mass percent of fly ash was 20%, the 60d gas permeability coefficient was 6.2 percent bigger than the ones when the mass percent of fly ash was 10%. The incorporation of ground slag or silica fume can decline gas permeability coefficient significantly. After freezing and thawing action, gas permeability coefficient of concrete increased with the frequency of freeze-thaw cycle. When the frequency of freeze-thaw cycle is 80, the gas permeability coefficient of C60 and C30 concreterose by 16.5 percent and 49.0 percent respectively.