Research On The Micromechanical Properties Of Recycled Waste Brick Concrete Based On A Triple Interface Layer

In China,there is a large amount of construction solid waste,but its utilization rate is very low.A large amount of construction waste has seriously harmed the environment affected the city appearance,and caused the dilemma of building waste siege.In the context of the national"dual carbon" strategy,there is an urgent need to improve the utilization rate of construction solid waste and strive to develop the recycling and utilization of construction solid waste.The use of recycled concrete technology can effectively alleviate increasingly prominent environmental problems,which can be achieved in one fell swoop.However,due to its own shortcomings,the various properties of recycled concrete are weakened,limiting the promotion of recycled concrete technology.Currently,most scholars use traditional physical tests to study the various properties of recycled concrete,but these studies are only limited to the macro level,and it is difficult to understand the impact of changes in its internal complex structure on the macro performance.It is difficult to further study its failure mechanism,and it is difficult to accurately grasp the performance of recycled concrete.In order to break through the technical bottleneck of physical experiments,this article develops a program based on Monte Carlo principles and PYTHON language,and runs it in the finite element software CAE environment.And construct a seven phase recycled waste brick concrete microstructure finite element model with a triple interface.The axial load is calculated and analyzed by taking the amount of waste brick,the strength of each phase component material,the thickness of interface zone and the thickness of old mortar as variables.The key influencing factors of the mechanical properties of recycled waste brick concrete are studied by using the Control variates.The main research results are as follows:(1)Based on PYTHON and ABAQUS,a mesoscopic numerical model of randomly concave convex waste brick recycled concrete composed of waste brick,crushed stone aggregate,new mortar,old mortar,crushed stone old mortar interface(ITZ1),new old mortar interface(ITZ2),and brick new mortar interface(ITZ3)has been established.By running the PYTHON script,micro numerical models with a total volume fraction of 35%,40%,45%,50%,55%,and 60%of coarse aggregate were automatically generated in CAE.And a model with a volume fraction of 45%coarse aggregate was selected to establish microscopic calculation models with brick quantities of 0,30%,50%,70%,and 100%.This indicates that the modeling method is convenient,efficient,and the developed script is practical and reasonable.(2)Grid density can affect the calculation results to a certain extent,and the trend of the stress strain curve resulting from different grid densities can vary.High grid density can lead to poor calculation accuracy,and the failure path of the specimen is minimally affected by grid size.Grid size does not affect the failure mode and final failure pattern of the specimen.With the increase in the number of bricks,the peak strain of recycled waste brick concrete becomes larger,the elastic modulus becomes smaller,and its macroscopic strength also changes.The addition of bricks will weaken the mechanical properties of recycled concrete,and the amount of bricks is 30%.(3)Under the action of uniaxial tensile(compressive)displacement,the stress nephogram of recycled concrete with different brick quantities will differ,and the location of the maximum stress concentration will vary.Each damage nephogram also has differences.Each damage cloud map also has differences,with different brick quantities and different damage and failure modes of recycled concrete.The first damage zone at the interface of fully recycled concrete bypasses the aggregate and is evenly distributed.The first damage zone of recycled concrete brick can penetrate the waste brick,but the first damage zone of recycled concrete brick bypasses the gravel aggregate and is mainly concentrated at the brick aggregate.The final form of damage is basically consistent.(4)The strength of recycled concrete with waste bricks is influenced by the strength of each phase of material,the interfacial zone,and the thickness of the old mortar.Increasing the strength of each component of the material will improve the strength of recycled concrete with waste bricks,while increasing the thickness of the old mortar and interface area will reduce the strength of concrete.