Air Permeability of Air-Entrained Hybrid Concrete Containing CSA Cement

This paper presents the results of research on series of concrete prepared with Portland cement CEM I 42.5R, with partial replacement of this cement with calcium sulfoaluminate cement. In part of the series, an air-entraining admixture was used. It was assumed that the mixture must remain workable for at least 45 min and to ensure that citric acid as the setting retarder was used. Compressive strength tests after 2, 7, 28, 56 and 90 days, tensile splitting strength test and sorptivity test after 28 days were performed. After 56 and 90 days, the moisture content of the specimens was determined, and Torrent air permeability was tested. Freeze-thaw scaling resistance was also investigated. It was found that the addition of 15% and 30% calcium sulfoaluminate cement results in a significant reduction in the relative humidity of the concrete, after storage under air-dry conditions and an increase in air permeability. The series with 30% calcium sulfoaluminate cement in the binder, regardless of aeration, showed significantly lower resistance to cyclic freezing in the presence of salt. A clear correlation between sorptivity, air permeability and surface scaling was not found. On the basis of a multi-criteria evaluation of the tested concrete and performed Performance Index calculations, the best parameters were achieved by concrete series C30-4.5.

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