| With the increase in service life of concrete structures, there are some damages inconcrete due to environmental effects, and then it may not meet the design requirements,so it needs to repair the existing structure. There are some drawbacks for the old methods of rehabilitation in view of durability, taking into account that ultra high performance concrete(UHPC) with excellent mechanical properties and durability, so it may be a good comprehensive repair method in both of mechanical properties and durability that UHPC is used as the repair material of existing concrete structure. It is crucial of bond behavior between new repair material and existing old concrete.However, it is not enough in research of interface bond behavior between the existing concrete and precast UHPC layer, especially lacking of interfacial behavior after freeze-thaw cycles. Based on above, both short term and long term(freeze-thaw cycles)interfacial behaviors are studied in this paper.The short-term load tests of interface bond behavior were carried out. The effect of adhesive material, shear key design and existing concrete strength on the behavior of interfacial bond and bond-slip were studied. The model of interfacial bond-slip is advised, and corresponding interfacial bond stiffness values of different parameters are also given. The oblique section shear tests were carried out to explore interfacial bond-slip behavior under pressure stress. The test showed that the shear strength and bond stiffness of oblique section shear tests have been greatly improved.The deterioration of interfacial bond with the freeze-thaw cycles was studied, and the results showed that degradation rates of interfacial bond stiffness are different with different repair design.The degradation formula of the interfacial bond strength, residual stiffness and degradation model of interface- slip are advised.On the basis of interface bond behavior research, existing RC parapets in the cold place were selected to research comprehensive rehabilitationanalysis of UHPC-RC parapets and this analysis is to reveal that the effect of interfacial design on long term performance of the existing RC structure.It can may provide a reference for the engineering rehabilitationdesign of this sustainable composite structure. |
