The effects of loading rates on the fracture characteristics at the bonding interface between steam concrete and self-compacting concrete using three-point bending test

Abstract

The properties of bonding interface of Chinese Railway Track System III (CRTS III) slab ballastless track structure is important for the stability of operation, however, little is known about the interface fracture behaviors of CRTS III slab ballastless track structure. In this work, the three-point bending test under different loading rates was conducted on concrete specimens with a bonding interface between steam concrete (SC) and self-compacting concrete (SCC). The influences of loading rate on the fracture parameters and characteristics were investigated. The experimental results indicate that the failure patterns of concrete with bonding interface changed from debonding failure to spalling failure as the loading rate increased. The P-CMOD curve of concrete with a bonding interface demonstrated a similar pattern under different loading rates, which mainly included three stages: linear growth stage, crack development stage and failure destruction stage. The fracture parameters exhibited an obvious loading rate effect: the higher the loading rate, the higher the fracture energy, as well as the critical relative effective crack length, fracture toughness, and the deformation resistance of the bonding interface. It also revealed that more tortuous main crack and multiple crack paths could be observed with the increase in loading rate. A higher loading rate can promote the conversion of fracture process zone to macroscopic crack zone and also increase the fracture energy in the bonding interface.