Mechanical behaviour of air-entrained concrete

Experimental investigation on the mechanical behaviour of air-entrained concrete under uniaxial compression, uniaxial tension, biaxial compression, biaxial tension-compression (T-C) and triaxial tension-compression-compression (T-C-C) loading conditions was carried out. The biaxial compression stress ratios α ₂ = σ ₂/σ3 = 0-25, 0-5, 0-75, 1-0, biaxial tension-compression stress ratios α ₁ = σ ₁/σ ₃ = -0-05, -0-1, -0-3, -0-5 and triaxial tension-compression-compression stress ratios α = σ ₁: σ ₂: σ ₃ = -0-25: 0-25; 1-0, -0-25: 0-5: 1-0, -0-25; 0-75; 1-0, -0-25: 1-0: 1-0 were selected as the major test variables. The failure characteristic of specimens and the direction of the crack are observed. Based on the test data, the biaxial ultimate strength envelopes and the failure criterion under triaxial T-C-C in principal stress space were proposed. The test results indicated that the strength of air-entrained concrete specimens under biaxial compression is higher than that under uniaxial compression and the maximum increase of ultimate strength occurred at a biaxial compression stress ratio of 0-5. The relationship between the ultimate compressive strength and stress ratio was given. It provides the experimental and theory foundations for strength analysis of air-entrained concrete structures.