Study on the interfacial bonding performance of basalt ultra-high performance concrete repair and reinforcement materials under severe service environment

The aim of this study was to investigate the effects of different curing conditions, interface types and new concrete types on the bond properties of new-old concrete bond specimens. The splitting tensile test, sulfate resistance dry/wet cycle test and salt freeze/thaw cycle test were carried out on four different types of new-old bonding specimens. The prediction model of splitting tensile strength of bonded specimens and the damage degree model of interface bonding strength based on damage mechanics under erosion environment were established. The results show that: (1) Curing conditions and interface types have a significant impact on the interfacial bond strength of new-old concrete bonded specimens. (2) Basalt fiber can significantly improve the bonding property. Nano-SiO2 was found to reduce the negative effects of low-temperature curing environment on the interfacial bond strength. (3) The degradation law of bond strength of specimens under corrosive environment shows that basalt fiber can improve the interfacial bonded durability of new-old concrete (4) Through the reconstruction and analysis of characteristic parameters of pore space network by CT scanning technology, it is found that basalt fiber was beneficial to retard the interface deterioration of bonded specimens under erosive environment.