Evaluation Of the Bond Strength Between the Old Concrete and The High-Performance Concrete (UHPC)Used in The Treatment by Slant Shear Testing

Abstract—This study investigates the bond strength between existing concrete, targeted for rehabilitation or strengthening, and high-performance concrete (UHPC). The research considers three compressive strengths for the existing concrete (C25 mpa, C35 mpa, and C45 mpa) and examines the effects of varying bonding angles (22°, 31°, and 40°) on the bond performance using the Slant Shear test. The findings indicate that bond strength significantly depends on the surface characteristics of the structural element and the bonding angle. An increase in the bonding angle by approximately 9° resulted in a 60% enhancement in bond strength across all compressive strength levels. Moreover, surface texture (smooth vs. Rough) influenced bond performance, with rough surfaces exhibiting a notable 20% increase in bond strength. The results further highlight the critical role of compressive strength in determining the overall bond performance. Keywords: Bond strength · Concrete · slant shear · high-performance concrete (UHPC) · Repair.