The microstructure evolution of ballastless track high-strength concrete exposed to compressive and flexural fatigue loads

Abstract

X-ray micro-CT method was applied to reveal the microstructure evolution of ballastless track high-strength concrete under fatigue loads. The CT image, porosity, pore volume distribution and aspect ratio of pores were analyzed. Results show that a visible crack is formed at stage II when concrete is under compressive fatigue loads. However, the pores around the interface transfer zone of compressive zone concrete are connected at stage III for concrete under flexural fatigue loads. As the microstructure of concrete is damaged and the single pores tend to be connected, the aspect ratio of pores is generally decreased during fatigue damage.