EFFECTS OF MICRO-FINES ON DURABILITY OF MANUFACTURED SAND CONCRETE

It was investigated that the effects of the different content micro- fines in manufactured sand on the compressive strength, permeability of chloride ion and resistance to freezing in different strength grade concrete.The result shows that the effects of the micro- fines on low and high strength concrete are not completely the same.To the low strength concrete, the resistance to chloride ion permeating of concrete is improved with the micro-fines content, but the resistance to freezing deduces.Especially when the micro-fines content is higher than 10% (ratio by volume of micro- fines and cement exceeds 1 B31 47), the degradation of manufactured- sand concrete is obvious; but to the high strength concrete, the workability becomes bad when the micro- fines content is higher than 7%.Whereas, to the durability of concrete, such as resistance to chloride ion permeating and resistance to freezing etc., there is no degradation in the high strength manufactured sand concrete when the micro fines content rises from 31 5% to 14%.