Study On Multiphase Mesoscopic Model Of Heterogeneous Characteristic Interface Of Concrete

Concrete is a widely used construction materials,its mechanical performance is closely related to the safety of building structure,characteristic and damage behavior of concrete material is the hot topic in academia and engineering continue,ceramsite concrete in recent years,as a new green material gradually widely used,its application can save valuable natural resources,the formation of resources recycling,achieve the goal of energy conservation and emissions reduction and low carbon environmental protection.Therefore,the analysis of the mechanical properties of concrete and ceramsite concrete has become a very important topic,and a large number of models and methods have been used to study this kind of problems.In this paper,the mechanical properties and damage behaviors of concrete and ceramicite concrete are studied.According to the physical properties of ceramsite,the mixing ratio of ceramsite concrete is designed.The basic mechanical properties of the two materials were measured.The strain values at different positions on the surface of the specimen were measured by the strain collection system,and the change process of the surface strain of the specimen during microcrack initiation was obtained.The crack behavior of the three-point bending beam specimen was qualitatively analyzed.The whole process of deformation and failure was tested by displacement loading method,and the complete load-displacement curve was obtained.Fuller grain grading curve was used to determine the volume fraction and number of aggregates.Based on MATLAB software,two-dimensional circular aggregate and three-dimensional spherical random drop were realized,and the geometric model of ceramsite concrete specimen with random distribution of aggregate was established.Thus,a mesoscopic finite element model of ceramsite concrete containing bubbles was established in ABAQUS software.Using CDP model as damage constitutive model of concrete and ceramsite concrete meso-component,the influence of parameter changes of concrete interface transition zone(ITZ)and bonding interface layer of ceramsite concrete on its mechanical properties and damage behavior is discussed by using homogeneous ITZ meso-model.The damage evolution process in concrete and ceramsite was obtained by numerical simulation,and the influence of microstructure and microstructure components on crack initiation and propagation was analyzed.The simulation results show that the properties of concrete ITZ,as a defect phase,will significantly affect the overall mechanical properties and damage and failure process of concrete materials,and the influence of the properties of the bonding interface layer of ceramsite concrete on its overall mechanical properties and cracking behavior is significantly reduced compared with that of ordinary concrete.Considering that the property of bonding interface layer of ceramsite concrete changes with the distance from aggregate,the mesoscopic models of ITZ heterogeneous concrete and ceramsite concrete are established,and ITZ performance gradient is changed.Compared with the simulation results of homogeneous ITZ model,heterogeneous ITZ model can more easily simulate multiple cracks,and the heterogeneity of ITZ model has certain influence on the morphological analysis of cracks.The simulation results show that a finer model considering ITZ heterogeneity can further improve the accuracy of the simulation results.According to the features of ceramsite concrete damage,the aggregates,cement mortar,is established between the bonding interface layer of bubbles and ceramsite concrete three-point bending beam finite element model,analyses the load under the action of the damage process of specimens,which will damage the specimen in the cracks form compared with the experiment,and verify the rationality of the model.The finite element model established in this paper can effectively analyze the internal damage evolution process of concrete and ceramicite concrete caused by the microstructure and components.The heterogeneity of ITZ makes the model analysis more precise and can effectively realize the analysis of the influence of the variation of the model's microstructure parameters on its overall mechanical properties.