Effect of nano-SiO2 modified interfacial agent on the bonding performance of concrete
The working performance of the concrete structure after repair and reinforcement was determined by the interfacial bonding performance of the new to old concrete.The interface agent was one of the effective ways to enhance the bond strength of new to old con-crete.The shearing test,splitting tensile test and scanning electron microscope(SEM)morphology analysis of the interface transition zone at the interface of new to old concrete were used to study the interface bonding effect of chiseling and five types of interface agents.The in-terface agent mainly included nano-SiO2 solution,nano-SiO2 mortar,mortar,butyl-benzene emulsionandepoxy resin.The mechanism of in-terfacial bonding performance of nano-SiO2 solution and interfacial agent of nano-SiO2 mortar was analyzed experimentally.The results showed that the 3.75%nano-SiO2 solution interface agent had the best effect on the repair of the new to old concrete interface,the interfa-cial transition zone was more fully hydrated and the net C-S-H gel was generated by the interface agent make the overall structure more compact.The highest oblique shear strength and splitting tensile strength at 28 d were 27.3 MPa and 6.3 MPa,respectively.The oblique shear strength was higher than the optimum roughness(6 mm)of 26.5 MPa.
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