A Review on the Bonding Properties of the Old-New Concrete Interface

Abstract

The bond performance at the interface between new and old concrete is critical for the repair and strengthening of concrete structures. This review systematically examines the core influencing factors and the resulting mechanical performance. The findings indicate that interface treatment through roughening methods is fundamental to ensuring bond quality, as it enhances mechanical interlock, often proving more effective than the sole use of bonding agents. Material modification, particularly the incorporation of ultra-high-performance concrete (UHPC), significantly improves the interfacial performance. The dense microstructure and high fiber content in UHPC effectively bridge micro-cracks, thereby substantially enhancing crack resistance, mitigating shrinkage, and increasing overall mechanical strength. Furthermore, the review underscores that optimal bond performance is achieved through the synergistic design of multiple factors, including surface roughness, bonding agents, fiber reinforcement, and curing regimes. Current research gaps are identified, particularly concerning the long-term durability under coupled environmental and mechanical loads, as well as the development of comprehensive theoretical models. Future research directions are briefly noted to address these challenges.