Crack extension resistance of concrete at low temperatures

Abstract

The process of determining crack extension resistance curves (KR curves) associated with the cohesive stress distribution for the complete fracture process of a three-point bending concrete beam at low temperatures from 20°C to −40°C is presented in this paper. A total of 32 concrete beams were divided into two groups, based on different ages, 28 d and 120 d. The KR curves were calculated from curves of load against crack mouth opening displacement obtained from test results of the concrete beams at low temperatures by considering the variation of the fracture process zone length. The weight function approach was used to replace numerical integration techniques to improve the computational efficiency. The calculation results show that the KR curves became higher with decreasing temperature and that the fracture process zone length had a significant influence on the KR curves. The stability of the KR curve and the influence of temperature on the fracture process zone length were also analysed.