Mechanical Damage and Freeze–Thaw Damage of Concrete with Recycled Brick Coarse Aggregate

The influence of different recycled brick coarse aggregate (RBA) substitution rates on the mechanical performance and frost resistance of concrete was observed. The test findings revealed that RBA deteriorated the compressive and flexural properties in concrete and improved the tensile properties and plasticity in concrete to some extent. The frost resistance of concrete can be effectively improved by adding RBA. The influence degree of the RBA concrete frost resistance factor was quantified by gray entropy correlation theory, and the gray entropy correlations between freezing and thawing cycles, natural coarse aggregate substitution rate, recycled brick aggregate substitution rate, and freezing and thawing damage value (DN) were 0.9979, 0.9914, and 0.9876, respectively. Moreover, the freezing and thawing damage model about GM(1, 1) theory was developed (R2 > 0.87), which can better predict the freezing and thawing damage of RBA concrete. The damage mechanism of RBA concrete during freezing and thawing was revealed.