Research On Bonding Properties And Mechanism Of Joint Interface Of Glued Precast Members

Segmental precast epoxied concrete bridge are characterized by higher quality of construction,rapid construction,around bridge site destruction of the natural environment of small,little impact on existing traffic under the bridge and the surrounding environment,etc.engineering applications gradually increased in recent years.Discontinuity of concrete and ordinary reinforcement at epoxied joints of segmental precast bridges.The bonding layer between epoxy resin and concrete is a weak point,which affects the bonding performance.In this paper,three kinds of interfacial bonding tests are carried out to study the bonding performance of glued members.The main contents and results are as follows:(1)The splitting tests of 108 150mmx300mmx 150mm interfacial bonded members were completed.The splitting failure phenomena of glue-bonded members were recorded in detail,and the strain and failure load of the tested members were tested during the test.The results showed that the interface splitting tensile member divided into three types of failure,i.e.adhesive layer destruction,mixed failure,cohesive failure.The splitting strength ranges of the three failure types are 0.66 MPa?0.98 MPa,1.43 MPa?1.96 MPa and 1.98 MPa-3.82 MPa,respectively.(2)The main influencing factors of the tensile properties of the interface of the component are analyzed,including the treatment method of the bonding surface,the size of the extrusion,the type of structural adhesive and the thickness of the rubber joint.The main factors affecting the tensile strength of the segmental rubber-bonded components were analyzed.The results show that the interface treatment has a significant effect on the interfacial bond tensile strength.The temporary extrusion stress and structural adhesive type have an effect but the effect is little affected.(3)The bending tests of six interfacial bonded structural members were completed,and the failure phenomena and failure loads of the glued members were recorded.The test results show that the failure types of flexural members are concrete within loading point,at glue joints and near joints.The average flexural strength of members is 5.36 MPa,which indicates that the glue joints have certain tensile properties.(4)Four interfacial glued members were tested under axial tension,and the failure phenomena and failure loads were recorded.The test results show that the failure type of bonded axially-tensioned members is cohesive failure,and the average tensile strength of bonded axially-tensioned members is 2.75 MPa,which indicates that the glued joints have certain tensile properties.(5)From the mesoscopic level,the microscopic structure of the fracture surface of the glued members was analyzed by optical microscope.The analysis results show that after the bonding surface treatment,the pores increase and the surface area increases;the epoxy resin is immersed in the pores of the bonding surface to form a tiny rivet structure,which enhances the bite cooperation between the epoxy resin and the concrete.Improve the bond strength of the bonding surface.(6)A BP neural network prediction model for the bonding strength of the joint interface of the prefabricated glued-bonded components is established.The prediction results show that the prediction accuracy of the member bond tensile strength prediction model can reach more than 85%.