Grey correlation analysis of macro- and micro-scale properties of aeolian sand concrete under the salt freezing effect

To study the effect of the pore structure of aeolian sand concrete (ASC) with different compositions on its compressive strength in a freeze-thaw environment, ASC with 0% (S0), 25% (S25), 50% (S50), 75% (S75), and 100% (S100) of aeolian sand (AS) content was prepared in our experiment. The damage and degradation laws of the compressive strength of ASC cube in the presence of chloride freeze-thaw were studied, and the compressive strengths of S0, S50 and S100 were predicted from the pore structure parameters. Compressive strength, nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) tests of the ASC samples were carried out. Grey correlation analysis was used to analyze the correlation between the pore structure parameters and the compressive strength, and a model was developed to predict the compressive strength of S0, S50 and S100 ASC subjected to freeze-thaw cycles (FTCs). It was shown that ASC with 25% AS content showed a large improvement in compressive strength, which was 6.86% higher than that of the S0 group. With the progression of FTCs, the porosity of ASC increases, and the bound fluid saturation and the proportion of 0-0.1 mu m pores decrease. According to the grey correlation analysis, the saturation of bound fluid and the proportion of 0-0.1 mu m pores have the strongest correlation with the compressive strength of ASC. The joint prediction model for the compression strength has a correlation coefficient of 0.937, and is able to better predict the compressive strength of ASC at different AS replacement rates during the FTCs.