Experiment and Analysis on the Strength of Large Aggregate Concrete under Biaxial Compression after Freezing-thawing Cycles

Biaxial compression tests are performed on 450mm*450mm*450mm cubic specimens of large aggregate concrete at five kinds of stress ratios,0:-1, -0.25:-1, -0.5:-1, -0.75:-1 and -1:-1 after freezing-thawing cycles of 50, 100, 150, 200, 250 and 300 times by the large static-dynamic true triaxial machine. The compressive strengths are obtained. Failure modes of the specimens are observed and described. Based on the test data, the influences of freezing-thawing cycles and stress ratios on the biaxial strengths of large aggregate concrete after freezing-thawing are analyzed respectively. The relationships between the ultimate compressive strengt, hs sigma 3 and freezing-thawing cycles, stress ratios are given respectively. The unitied failure criterion considering the influence of freezing-thawing cycles and stress ratios is proposed, which provides the experimental and theoretical foundations for strength analysis of large aggregate concrete structures subjected to complex loads in cold environment.