Abstract: The degradation rule of concrete damage layer subjected to drying-wetting cycles in different types of sulfate solution was studied in the paper. Moreover, the mechanical properties of the damage layer was analyzed. Then the compressive strength of concrete in damage layer was obtained. The experimental results showed that the ultrasonic velocity in the damage layer decreased and the surface damage layer thickness of concrete increased with corrosion time, and the compressive strength in damage layer reduced obviously. When the damage layer thickness of concrete is thicker and the ultrasonic speed is lower, indicating that the deterioration degree of concrete increases. The concrete deterioration by magnesium sulfate covers the most aggressive corrosion, the damage layer thickness of concrete is the largest, and its compressive strength reduces obviously. The damage layer thickness of concrete in composite solution of Na2 SO4 and NaCl is the least, and the decrease of compressive strength is the lowest. The presence of chloride ions reduces the degradation degree of concrete under sulfate attack.

Key words: concrete;sulfate corrosion;drying-wetting circulations;damage layer thickness;chloride