Bond shear fatigue behavior between ultra-high-performance concrete and normal strength substrate

In this study, the bond fatigue performance of ultra-high-performance concrete (UHPC) and normal-strength concrete (NSC) repair material is investigated based on the roughness factor. A single-side shear test is performed to evaluate the bond fatigue performance under stress levels of 0.7, 0.8, and 0.9. The results indicate that the NSC-NSC specimen exhibits a bond failure mode, whereas the UHPC-NSC specimen exhibits substrate failure or substrate and bond mixing failure. Roughness is a key factor affecting bond fatigue life. Fatigue life prediction equations for UHPC-NSC and NSC-NSC are developed. The overlay transition zone of UHPC-NSC is denser than that of NSC-NSC.