Simulation of surface preparations to predict the bond behaviour between normal strength concrete and ultra-high performance concrete

•Experimental study on effect of surface preparation on bonding between NSC and UHPC.•Surface preparation (chip/groove) and nature of bond (fresh/harden state of UHPC)•Numerical models used to evaluate the composites with complex surface preparations.•Complex interactions is eliminated by assuming prefect bonding in numerical studies.•SEM analysis confirm uniform and well-structured groove leads to exhibits better bond. Bond strength between the normal strength concrete (NSC) and ultra high performance concrete (UHPC) is determined through slant shear, split tensile and four point bending test. Test methods are selected based on failure criteria such as shear, tension and bending in the typical strengthened structural components. The parameters studied to determine the bond behaviour are surface preparation (chipping and grooving) and nature of bonding (fresh and hardened state of UHPC) are chosen based on the bond studies carried out by many researchers. However, numerical research is required to evaluate the performance of the composite members incorporated with various surface preparations. Hence, the experimental results of composites with different surface preparations are validated through numerical approach by predicting the maximum failure load. The maximum difference between the numerically predicted and the corresponding experimental value is about 12%. Scanned electron microscopic analysis has been performed to determine the morphology of bond surface.