Study on Fracture Characteristics at the Interface between Steam Concrete and Self-Compacting Concrete Under Different Loading Rate

Abstract

To further study the interface damage and fracture mechanism of plate-type ballastless track, a three-point bending test under different loading rates was carried out on concrete specimens with bonding interface between steam concrete (SC) and self-compacting concrete (SCC), using DIC technology. The influence of loading rate on the fracture parameters and characteristics was obtained. 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 typical P-CMOD curve of concrete with bonding interface has gone through three main stages: linear growth stage, crack development stage and failure destruction stage, and the shape of the P-CMOD curve does not change with the increase of loading rate. The fracture parameters of concrete with bonding interface have an obvious loading rate effect, the higher the loading rate, the higher the strain rate, as well as the fracture energy, critical relative effective crack length, fracture toughness, and the deformation resistance of the bonding interface. Also, there was a linear relationship between the dynamic fracture toughness enhancement factor and the logarithm of strain rate enhancement factor. The crack deflection and multiple paths were observed by DIC, the higher the loading rate, the larger the tortuosity of the route of main crack path. A higher loading rate can promote the conversion of fracture process zone to macroscopic crack zone and increase the fracture energy in the bonding interface.

Keywords: Concrete with bonding interface, fracture process, loading rate, digital image correlation