| The near-surface-mounted CFRP reinforcement technology is a method of making grooves on the surface of components and embedding CFRP slots into the slots through epoxy resin adhesive to make the FRP and components bear forces together.The near-surface-mounted CFRP reinforced concrete(CFRP)has become a research hotspot in recent years because of its increased bond area,better bond performance and stronger resistance to external interference.In the reinforced structure,the shear stress between concrete and FRP mainly depends on binder to form a co mmon force as a whole,so the bond interface between CFRP and concrete becomes the key interface in the reinforced structure.Most scholars have studied the interfacial bond performance of surface embedded CFRP-concrete,and the results show that the service temperature(test temperature)and binder curing temperature have a great i Mpact on the interfacial bond performance of surface embedded CFRP reinforced structures,but there are few studies in this area,and no widely recognized conclusions have been reached.Therefore,in order to further promote the application of the near-surface-mounted CFRP strengthening technology,this paper studies the bond performance of the near-surface-mounted CFRP-concrete interface at different test temperatures and curing temperatures:(1)Starting from the performance of the binder itself,the uniaxial tensile shear test of epoxy resin was carried out to study the effects of different test temperatures and curing temperatures on the colloid properties and bonding properties of epoxy resin.The results showed that:Curing temperature has little effect on colloidal properties and bond properties.Increasing curing temperature can accelerate the curing process of epoxy resin,greatly shorten the curing time,and the improvement of curing temperature can also improve the heat resistance of epoxy resin.Test temperature had a greater influence on the gel properties and bonding performance of epoxy resin,the colloid performance with the increase of test temperature significantly decline,the temperature reaches 80℃,colloid basic has lost its strength,the bonding performance with the increase of test temperature rise after the first decline trend,the glass transition temperature and test temperature of epoxy resin adhesive performance began to decline.(2)A single shear and pull-out test of CFRP-reinforced concrete test block was conducted to study the bond properties of CFRP-concrete interface at different test temperatures and curing temperatures,and the test was analyzed in combination with the colloidal and bond properties of epoxy resin.The results showed that:The curing temperature has little influence on the bonding performance of the interface,and the efficiency of strengthening can be improved by increasing the curing temperature,and the heat resistance of the bonding interface is better under high temperature curing.The experimental temperature has a great influence on the interfacial bond performance.The interfacial bond performance decreases obviously at high temperature,and the decline trend is most obvious when the temperature reaches the conversion temperature of epoxy glass.(3)The single shear and pull-out tests of the near-surface-mounted CFRP reinforced concrete test block were carried out at different test temperatures.The bond slip constitutive model of the interface between the near-surface-mounted CFRP and concrete was established at different temperatures.The constitutive model was carried out in ABAQUS finite element for numerical simulation,and the finite element simulation results were in good agreement with the test results. |
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