纳米SiO_(2)改性界面剂对混凝土黏结性能的影响

Effect of nano-SiO_(2) modified interfacial agent on the bonding performance of concrete

混凝土结构修补加固后的工作性能取决于新旧混凝土的界面黏结性能,增强新旧混凝土黏结强度的有效途径之一是使用界面剂。通过新旧混凝土界面的斜剪试验、劈裂抗拉试验和界面过渡区SEM形貌分析,对比研究了纳米SiO_(2)溶液、纳米SiO_(2)砂浆、砂浆、丁苯乳胶、环氧树脂5种类型界面剂以及凿毛处理的界面黏结效果,分析了纳米SiO_(2)溶液、纳米SiO_(2)砂浆作为界面剂提升界面黏结性能的机理。试验结果表明:3.75%纳米SiO_(2)砂浆界面剂对新旧混凝土界面的修补效果最好,其界面过渡区的水化反应更充分,生成的网状C-S-H凝胶使得整体结构更加紧密,28 d的斜剪强度和劈裂抗拉强度最高,分别为27.3 MPa和6.3 MPa,其斜剪强度甚至比最优粗糙度(6 mm)26.5 MPa要高。

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-SiO_(2) solution,nano-SiO_(2) mortar,mortar,butyl-benzene emulsionandepoxy resin.The mechanism of in-terfacial bonding performance of nano-SiO_(2) solution and interfacial agent of nano-SiO_(2) mortar was analyzed experimentally.The results showed that the 3.75%nano-SiO_(2) 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 spliting 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.