Effect On Moist-Curing Time At Early Ages And Ordinary Concrete Contains Fly-Ash Contentson Carbonation Resistance

pH value is generally greater than12.5inside concrete which protects the steel against erosion for it provides the alkaline condition. Carbonization is a key factor that makes alkalinity of Concrete reduces. With the development of our country’s economy, pumpcrete was increasingly widely used in practical engineering. The effect of moist-curing time at early ages and the content of mineral admixture on the compressive strength and the carbonation resistance of fly ash (FA) contents were studied in this thesis. Based on compressive strength test and accelerated carbonation test, the variation of compressive strength and carbonation resistance of fly ash (FA) contents with moist-curing time at early ages.Results of the experiments indicate:(1) Firstly, based on compressive strength test,the thesis analyzes the influence of moist-curing time and contents on fly ash (FA) contents concrete by the way of microcosmic analyses and theories.(2) Secondly, based on accelerated carbonation test, the thesis analyzes the improvement of fly ash、slag and superplasticizer on the carbonization resistance. Under the same condition of water binder ratio, the type and content of mineral admixture, the carbonation resistance of concrete decreased obviously with a reduction in moist-curing time at early ages. Under the same condition of water binder ratio, the type of mineral admixture and moist-curing time at early ages, the carbonation resistance of concrete decreased with an increase in the content of mineral admixture.(3) A linear relationship exists between concrete carbonation coefficient and concrete strength grade, and a power function relationship exists between the carbonation coefficient and moist-curing time at early ages.(4) Then, based on accelerated carbonation test with two different cement42.5,52.5grade, the thesis analyzes the carbonation resistance of fly ash (FA) contents.(5) Finally for the compressive strength and the carbonation resistance of ordinary pumpcrete, it is necessary that the moist-curing time at early ages should need7days and the content of mineral admixture should not go beyond the corresponding limit.