Salt-Frost Resistance Performance of Airfield Concrete Based on Meso-Structural Parameters

Airport cement pavement is prone to severe freeze-thaw damage due to the use of deicing chemicals. There is no unified evaluation parameter for analyzing the relationship between the concrete meso-structure and its salt-frost resistance. Therefore, industrial computed tomography (CT) scanning technology was applied in this study to obtain the meso-structure of concrete and the meso-structural parameters of concrete (air content, air void surface area per unit volume, air void distance factor, air void volume fractal box dimension, air void surface area fractal box dimension) that are introduced to characterize its meso-structure. The relationship between each structural parameter and the salt-frost resistance of concrete were analyzed, and a gray correlation model was established to quantitatively compare the significance of each parameter. In addition, the meso-structural parameters were used to analyze the internal structural changes of concrete under freeze-thaw cycles; this analysis mainly included three aspects. First, changes in concrete meso-structure before and after freeze-thaw cycles were analyzed. Second, changes in each meso-structural parameter of concrete under freeze-thaw cycles were tested and calculated. Third, a damage degree index, based on the air void surface area fractal box dimension, was proposed for characterizing the damage degree of concrete. The results showed that air void distance factor had the most significant influence on the salt-frost resistance of concrete in each structural parameter and could be used as the characterization parameter. The depth of the influence of salt frost on the internal structure of non-air-entrained concrete was deeper than its influence on air-entrained concrete. In addition, the damage degree index can quantify the degree of deterioration in concrete meso-structure well.