Property analysis of concrete under coupling action of sulfate and wet-dry cycles

Under the coupling action of wetting-drying cycles and sulfate, analysis studies of the effects of mineral admixture types, dosages and air content on mass loss, compressive strength and relative dynamic elastic modulus of concrete have been carried out. From the fourth wet-dry cycle, the quality loss of concrete specimens adding the mineral admixtures is less than that of benchmark concrete, and the reduction quality loss of the specimen mixed with ore powder is much greater; through the third dry-wet cycle, the increase in the compressive strength of the concrete specimens adding the mineral admixtures is greater than the benchmark concrete, and the reduction quality loss of the specimen mixed with ore powder is more remarkble; after the sixth wet-dry cycle, the relative dynamic elastic modulus of the concrete specimen adding mineral admixtures still remains over 60%; and mixing fly ash and mineral powder into the concrete specimens can effectively increase the resistance of the concrete specimens to damage caused by sulfate and wetting-drying cycles， thus improving concrete durability. With the composite dosage (the mix proportion of fly ash and mineral powder is 3:1) adding into the concrete specimens, the improved effects of the compressive strength of concrete are much more significant. At last, air entraining into the concrete specimens can improve the resistance of concrete to sulfate in the wet-dry cycles.