Early prediction of concrete resistance to freezing - thawing impact

Concrete structures should be designed and built in the way that, under expected environmental conditions, their safety and usability hold over the structures lifetime with minimal repair and maintenance cost. Long-life concrete must be resistant to destruction when exposed to aggressive environment like it is, among other things, the freezing effect with or without de-icing salt. The aim of this paper has been the analysis of theair void parameters in fresh concrete and proving of the concrete resistance to the freezing and thawing effects already in fresh concrete. Twenty two concrete mixtures have been prepared and all the concretes physical and mechanical properties have been tested. Mixtures are prepared with two cement types and one type of air entraining admixtures. The assessment of concrete resistance obtained in fresh concrete is compared with assessments obtained in hardened concrete. By means of an air pores analyzer, it is proved that it is possible to make necessary corrections of the concrete composition in the mixing stage and avoid additional cost of repair works. With a proper pre-selection of concrete components by the AVA method, a reliable perception of the resistance to freezing in fresh concrete is possible already during mixing. Also checking by the microscopic method in hardened concrete has significantly reduced time necessary for the excecution of preliminary testing by the alternating freezing and thawing cycles.