Performance of Cement Asphalt Mortar in Ballastless Slab Track over High-Speed Railway under Extreme Climate Conditions

Abstract

The cement asphalt (CA) mortar layer acts as the key component of the China Railway Track System II (CRTS-II) type ballastless slab track to ensure stability, durability, and cost maintenance. However, it was found to be easily degraded during operation, particularly under extreme climate conditions. In this paper, to study the performance of CA mortar under extreme temperatures, flexural strength and fatigue tests were conducted to evaluate its mechanical properties. Moreover, the stress and deformation of the track under different temperature loads were analyzed based on the temperature fields, which were simulated through a transient thermal analysis. The results show that the flexural strength and fatigue life are reduced by high temperatures, and the highest possible temperature on the surface of the track can reach 58.8°C in China. The maximum principle stress can reach 1.2 MPa under the negative temperature gradient load, which is three times larger than under the train load and is close to the flexural strength obtained from the tests. As a result, the degradation of CA mortar is mainly caused by the increase of the stress and the deterioration of the tensile capacity induced by the extreme climate.