Method for prediction of the frost resistance ability of air‐entrained concrete based on the 3D air void characteristics by x‐ray micro‐CT

Abstract

In modern construction, one of the most important factors in the execution of contracts is time. Standard procedures for assessing the frost resistance or concrete are usually very time‐consuming and can take up to 40 days. The current paper is experimentally and practically oriented. It presents an alternative testing method, based on air void network, that allows to assess the frost resistance of concrete within just a few days of taking the samples. X‐ray micro‐CT scans were introduced to obtain the quantitative and qualitative 3D information about the air void microstructure taking into account total air content: A (%), pores of the size below 300 μm in diameter content: A300 (%), specific surface of air voids: α (mm−1) and spacing factor: L (mm) to predict the freeze/thaw durability. To verify the assumptions of the frost resistance method, based on the analysis of pore microstructure, tests of freeze/thaw resistance in accordance with Polish supplement to European Standard were carried out. Presented research revealed that the appropriate microstructure of air pores, in particular, content of micropores with the diameter less than 0.3 mm: A300 combined with a spacing factor: L (mm) can constitute a reliable basis for determining concrete freeze/thaw durability. Thus, the method proposed in the current paper can be effectively used for fast and trustworthy determination of the air‐entrained concrete durability in a short time and without any special preparation of the tested sample that allows immediate preventive or repair actions to be taken if required.