Influence of interface joint types on shear bond strength between ultra-high performance concrete and normal concrete

This research aims to investigate the influence of groove interface joint types on shear bond strength between ultra-high performance concrete (UHPC) and normal concrete (NC) via push-out test. Nine specimens with two different types of interface joints, smooth and groove joints with/without bonding agent (BA), were tested. The experimental results indicate that the shear bond strength between UHPC and NC varies significantly based on the interface conditions. Among the interface joints, groove joints showed higher shear bond strength compared to smooth joints. The study also highlighted that increasing the groove width for NC enhances interface shear bond strength, while increasing the groove depth reduces it. Additionally, the application of a BA improves the bond strength between UHPC and NC, significantly in smooth surface conditions, but provides much less effectiveness in the grooved interfaces. These findings underscore the importance of interface design in optimizing the interface shear bond strength between UHPC and NC.