Interface Shear Behaviour between Precast and New Concrete in Composite Concrete Members: Effect of Grooved Surface Roughness

A major condition for the quality performance of connected-concrete layers is enough shear strength at the interface. Research shows that the interface shear behaviour is highly dependent on the texture of its interface. Although, several research on the effect of surface roughness on the interface shear behaviour of concrete to concrete connection using different interface patterns exists; however, there is scant literature on studies using quantitatively controlled interface texture, especially studies considering the roughness tooth geometrical parameters. In this study, seven different interface roughness geometries were designed and utilised as the study parameters for the interface shear behaviour, as well as the initial confining pressure. The double-sided shear test was used to determine the shear behaviour, failure mode, shear transfer mechanism, alongside the friction and cohesion values for all the studied interface types. The test results showed that both the interface roughness geometry and the magnitude of the confining pressure have a significant effect on the interfacial shear behaviour. Using different formations of the interface geometry provided a 15.4% difference in interfacial shear strength. For most of the interface geometries, interface cracking load increases linearly with the increase of initial confining pressure, while for the shear strength, the increase in confining pressure is more effective at lower pressure values. The friction and cohesion coefficients are influenced by the roughness tooth angle and tooth distribution.