Evaluation of the Fracture Properties of the Bond Interfaces between UHTCC Overlays and Concrete Substrates

Ultra high toughness cementitious composite (UHTCC) overlays can be used for durability repair of deteriorated concrete structures since they have a strain hardening property, super ductility and multiple cracking behaviors. A key issue for this repair technology is the behavior of the interfacial bond between the UHTCC overlay and the concrete substrate. In this paper, the fracture properties of the bond interfaces between UHTCC overlays and concrete substrates were evaluated through four-point bending tests, which were conducted on a series of notched concrete beams externally bonded with UHTCC overlays. The influence of the interface configuration on the interfacial fracture properties was investigated. It was found that a multilayered bonding system with the use of prefabricated UHTCC led to better fracture performance of the bond between the UHTCC overlay and the concrete substrate in terms of both the strength and deformability as compared to a cast-in-situ one. Therefore, such a bonding system may become an ideal solution for the durability repair of aged concrete structures.