Under the condition of drying and wetting circulation, ordinary concrete, modified concrete containing fly ash, and double-admixture concrete containing fly ash and polypropylene fiber were corroded in the solution of Na2SO4 and (NH4)2SO4. The sulfate concentration of the solution was designed to be 1000 g/L. The compressive strength and splitting tensile strength of the concrete were tested after different number of drying and wetting cycles (0, 2, 4, 6, 8, and 10). The results indicate that the strength of concrete increases in the early stages of corrosion and decreases gradually later. The admixture significantly improves the resistance to sulfate erosion of the modified concrete, while polypropylene fiber plays a less important role on anticorrosion properties. When suffered 10 times of drying and wetting cycle, the compressive strength and splitting tensile strength of modified concrete increase by 28% and 19%, respectively. Based on the test results, the service life of the modified concrete corroded by sulfate was predicted.
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