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

Abstract

Biaxial compression tests are performed on 450mm*450mm*450mm cubic specimens of big aggregate concrete at five kinds of stress ratios,0:-1, -0.25:-1, -0.5:-1, -0.75:-1 and-1:-1 after exposure to freeze-thaw cycles of 50, 100, 150, 200, 250 and 300 times by employing a large static-dynamic true triaxial machine. Failure modes of the specimens are observed and described. The two principally static compressive strengths are measured. Based on the test data, the influences of the freeze-thaw cycles and stress ratios on the biaxial strengths of big aggregate concrete after exposure to freeze-thaw are analyzed respectively. The relationships between the ultimate compressive strength and freeze-thaw cycles, stress ratios are given respectively. The unified failure criterion with consideration of the influence of freeze-thaw cycles and stress ratios is proposed, which provides the experimental and theoretical foundations for strength analysis of big aggregate concrete structures subject to complex loads in cold environment. Key words: big aggregate concrete; freeze-thaw cycle; stress ratio; biaxial compressive strength; failure criterion