Interface Shear Strength between Ultra-High-Performance Concrete and Normal-Strength Concrete

Abstract

Section enlargement and jacketing using ultra-high-performance concrete (UHPC) have been used to strengthen existing reinforced concrete structures. The structural performance of these strength-ened structures is highly dependent on the bond performance at the interface between the UHPC and normal-strength concrete (NSC) substrates. This study investigates the shear strength and ultimate failure mode of the interface in UHPC-NSC composites using an experimental program of slant shear test. The main test parameters include the roughness and inclination angle of the interface and the curing condition of the UHPC. Both the roughness at the interface due to sand-blasting and the inclination angle of the interface control the failure modes showing distinct transitions of the failure modes between concrete crushing and near-interface concrete cracking. The failure criteria for the interface of UHPC-NSC composites can be explained using the theory of plasticity by identifying the failure modes.