A new test method for freeze–thaw resistance of ballastless track structure concrete: experiment and model

摘要

Existing methods for evaluating the resistance of concrete to freeze–thaw cycles might not be suitable for concrete used in ballastless track structures (BTSs). In this study a new test method was designed to investigate the freeze–thaw resistance of concrete used in BTSs: the test procedure, the specimen size and the position of the test surface were all redesigned. The results showed that the accumulated scaling mass could reflect the freeze–thaw resistance of BTS concrete better than the relative dynamic modulus of elasticity. Parameter analysis was conducted to shed light on relationships between the accumulated scaling mass and slump, laitance depth and position of test surface and some fitting equations were established. Based on the experimental results, a model of freeze–thaw fatigue life for BTS concrete in cold regions was proposed and verified. According to the calculated fatigue life data, the slump and test method/mould size were the two most significant factors in the freeze–thaw resistance of concrete. In addition, the freeze–thaw resistance of BTS concrete was found to be overestimated by the existing test method; the reason for this overestimation is explained.