Usually repair systems can be divided into three different phases of materials -- repaired substrate phase, repair material phase and the interface phase between substrate and repair material. Each phase of material has to have its own role in the…
Usually repair systems can be divided into three different phases of materials -- repaired substrate phase, repair material phase and the interface phase between substrate and repair material. Each phase of material has to have its own role in the system for durable repair. Among the three phases, the interface phase especially has the most important role to integrate the repair systems. Recently, interface properties -- bond strength and interface fracture toughness, etc. -- were focused on to predict the performance of repair systems. In this paper, the interface between old concrete as a repaired substrate and repair material based on cementitious composites is characterized using interface fracture mechanics. The interface fracture toughness is experimentally measured with three potential repair materials -- plain concrete, steel fiber reinforced concrete (FRC), and engineered cementitious composite (ECC). Furthermore this measured interface property is utilized theoretically to predict the interface fracture behavior. Based on this prediction, a trapping mechanism is discovered and this mechanism is experimentally demonstrated in representative repaired concrete infrastructures to show stronger, more ductile, and more energy absorbing repair system in comparison to the other potential repair systems.