Review Study on the Interface between Ultra-High Performance Concrete and Ordinary Concrete

Ultra High-Performance Concrete (UHPC) based on RPC configuration technology The research on material properties, structural components, and engineering practice has become one of the research hotspots of cement-based materials today. This paper summarizes the test methods of UHPC-NC interface bonding performance at home and abroad, the calculation formula of interface shear strength, the influencing factors, and the research progress of interface high-temperature resistance introduces the test method of UHPC-NC interface bonding mechanical properties and summarizes. The influence of different factors on the bonding performance of UHPC-NC interface, including fiber, interface roughness, interface moisture content, interface agent, existing concrete strength, cementitious material, and curing system, etc. The results show that: UHPC-NC has excellent interfacial bonding strength, among which, the appropriate curing system and fiber can reduce the shrinkage of UHPC and enhance the compatibility between materials; the increase of interface roughness and existing concrete strength can effectively avoid interface destruction; interface agent, interface water content and gelling material can improve the transition zone; UHPC-NC interface has good anti-permeability and anti-freeze-thaw performance; the incorporation of polypropylene fibers can improve the anti-burst performance of UHPC, and the mixed incorporation of different types of fibers can also reduce the high-temperature burst of UHPC. At present, there are many evaluation criteria for the mechanical properties of UHPC-NC interfaces, but there is a lack of research on the high-temperature resistance of UHPC as a repair material and UHPC-NC interfaces after high temperature.