Study on Concrete Freezing-thawing Damage Layer Considering Residual Strength Correction and Constitutive Model under Axial Compression

In this paper, the assessment method and the axial compression performance of concrete under freezing and thawing conditions were studied by air-freezing and air-thawing test in accordance with the actual freezing and thawing environment. The freeze-thaw damage layer thickness was measured by ultrasonic single side method. The freezing-thawing damage layer was used as an index to evaluate the freezing-thawing damage degree of the concrete. Based on the residual strength in concrete damage layer, the damage layer correction coefficient α was introduced to improve the reliability of damage degree evaluation. Following the discussion of the damage evolution law, the constitutive model of concrete under axial compression based on freeze-thaw damage layer was established. The results show that after introducing the correction coefficient α, the evaluation accuracy of freezing-thawing damage degree is improved significantly. With the increase of freezing-thawing cycle, the correction coefficient α decreases gradually, which reflects that the residual strength in the damaged layer decreases and the actual damage degree increases gradually. After the peak point, the higher the compressive strength of the concrete, the faster the evolution rate of the total damage degree (freeze-thaw damage and load damage) is. The results of the constitutive model are in good agreement with the experimental results in this paper and other literatures. © 2021, Department of Journal of the China Railway Society. All right reserved.