Research On Interfacial Properties And Microstructure Of Composite Concrete

In the manufacture of high-precision CNC machine tools,the gradual replacement of the traditional cast iron bed by polymer concrete bed has become the mainstream trend in the world.Although the new material has the advantages of good dynamic characteristics,strong anti vibration ability,good stability and high processing precision,it can not be popularized in view of the reason that its manufacturing cost is much higher than that of cast iron.To solve this problem,Professor Ding Jiangmin of Dalian Jiaotong University proposed a new type of composite concrete for machine tool bed.In the current application research,it is found that the composite concrete bed is prone to interface cracking near the guide rail under long-term load conditions.The direction of the guide rail is the main bearing direction of the lathe bed,which requires the material to have a high bearing capacity along the guide way.In order to solve the cracking problem of machine bed,solid composite interface has become the key technology to improve the performance of composite concrete.In order to study the composite interface,the work of this paper is as follows:(1)In this paper,the epoxy resin concrete(EPC)is used to coat and bond the precast core of high strength silicate concrete by compression molding method,so that the composite concrete material can be obtained through the steps of vibration,maintenance and aging.A new type of joint model is proposed from the perspective of geometrical factors.And the test specimens were obtained by the method of press molding.(2)The static mechanical tests such as compressive strength,splitting strength and surface hardness were carried out.The interface was modeled by mathematical model.The MATLAB was used to analyze the experimental results and optimize the interface to get the optimal solution of the interface shape.The optimal state interface is applied to the prototype manufacturing.Prototype mold manufacturing,steel structure design,interface treatment and casting molding are completed.(3)JSM-5610LV scanning electron microscope(SEM)was used to observe the interface fracture morphology and analyze the microstructure of the interface.The mechanism of interfacial bonding and optimization are explained from the microscopic structure,which provides a theoretical basis for this experiment.According to the above work,the conclusion is as follows:(1)Through the interface optimization,the static mechanical properties of the composite concrete are higher than that of the silicate concrete and the composite concrete with the plane adhesion.Although it is slightly inferior to the epoxy resin concrete,it can meet the requirements of the application and have a higher cost performance.(2)Through the curing reaction of EPC matrix,the composite concrete was formed by epoxy colloid and gel,and finally formed a three-dimensional cross-linked network structure.The degree of reaction of active functional groups is related to crosslinking density,terminal entanglement of molecules,chemical bonding and intermolecular force.The EPC matrix forms a composite interface with the surface of silicate concrete through infiltration,adsorption and chemical bonding.The interface strength is related to the morphology and arrangement of the microgel in the inhibition layer and the interface zone.The micelle density and its ordering in the inhibition layer directly affect the modulus and deformation of the resin in the layer,thus affecting the load bearing capacity of the interface.Wave joint not only has higher coverage rate and adsorption activation energy,but also has higher functional group reaction.The proportion of large gel is larger and the arrangement is more compact,which makes the wave joint have higher bonding strength.And its lateral carrying capacity is 70.2%higher than the horizontal interface.It can be considered as an effective way to solve the interface cracking problem.