INVESTIGATION OF FROST RESISTANCE OF FLY ASH CONCRETE WITH AIR-ENTRAINING ADMIXTURE

摘要

In the paper the impact of the simultaneous action of fly ash and air entraining admixture on the concrete frost durability has been presented. The experiment included 12 series of concrete, which contained a variable amount of air-entraining admixture and fly ash. Some characteristics of freshly mixed concrete such as consistency and air content were assessed. Tests of the hardened concrete included compressive strength and frost resistance. Furthermore, the pore structure of concrete was tested. Parameters such as: the total air content in concrete A, average spacing factor between air voids _L and content of micropores A(300) were determined. Based on the obtained results, it was found that the fly ash and air entraining admixture are essential for concrete durability during cyclic freezing and thawing. The relationship between the directly tested concrete frost resistance and air void structure in hardened concrete was shown. The conducted tests confirmed that fly ash concrete obtains proper frost resistance thanks to the appropriate use of air entraining admixture.