Influences of Erosion Modes on Sulfate-ion Transportation in Concrete

The erosion modes of both continuous immersion and wetting-drying cycles were selected to study their effects on the transportation process of sulfate-ion in concrete.The strength grade of concrete was C40,the natural dry mode in room temperature was used.The concentration of sodium sulfate solutions were 800 mg/L,6000 mg/L and 50 000 mg/L respectively.With the erosion ages of 30 d,90 d,180 d,360 d and 580 d,the samples were made by drilling core,cutting into slices and grinding into powder,and tested by the chemical analysis method.In comparison with continuous immersion,the wetting-drying cycles can generally accelerate the sulfate-ion transportation into concrete in deep,and increase the sulfate-ion content in the same depth of concrete.The sulfate-ions in erosion solution of lower concentration tend to be transported into deep place of concrete where the sulfate-ion content will be increased.The erosion solution of high concentration tends to generate concrete failure from the exterior to the interior,so much more sulfate-ions are gathered in the shallow layer of concrete.