Effect Of Moist-curing Time At Early Ages On Carbonation Resistance Of Ordinary Pumpcrete

The effect of moist-curing time at early ages and the content ofmineral admixture on the compressive strength and the carbonationresistance of ordinary pumpcrete were studied in this thesis. Based oncompressive strength test, the variation of compressive strength of ordinarypumpcrete with moist-curing time at early ages and the content of mineraladmixture was studied. Based on accelerated carbonation test, the variationof carbonation resistance of ordinary pumpcrete with moist-curing time atearly ages and the content of mineral admixture was studied.Results of the experiments indicate:（1）Under conditions of28dstandard-curing, the compressive strength of C30grade concrete incorporat-ed with slag or fly ash increased at first and then decreased with anincrease in the content of mineral admixture, and the compressive strengthof C40grade concrete incorporated with slag or fly ash and the C30or C40grade concrete incorporated with slag and fly ash decreased with anincrease in the content of mineral admixture.（2）With the same content ofmineral admixture, the compressive strength of C30or C40grade concretedecreased with a reduction in moist-curing time at early ages.（3）Underconditions of different moist-curing time at early ages and differentcontents of mineral admixture in C30or C40grade concrete, the accelerat-ed carbonation depth D and the accelerated carbonation time t were shownto satisfy the general formula: D=kt0.5.（4）Under the same condition ofwater binder ratio, the type and content of mineral admixture, the carbona-tion resistance of concrete decreased obviously with a reduction inmoist-curing time at eraly ages.（5）Under the same condition of water binder ratio, the type of mineral admixture and moist-curing time at earlyages, the carbonation resistance of concrete decreased with an increase inthe content of mineral admixture.（6）For the compressive strength and thecarbonation resistance of ordinary pumpcrete, it is necessary that themoist-curing time at early ages should need7days and the content ofmineral admixture should not go beyond the corresponding limit.