Experimental Study And Meso-damage Propagation Analysis Of Reinforced Concrete Under Corrosion Expansion

Reinforced concrete is one of the most important materials in the field of civil engineering.Its performance is greatly affected by the surrounding environment.In the humid and multichemical salts environment,it will promote the corrosion of reinforced concrete and lead to structural damage and failure.Therefore,it is necessary to study the mechanism and process of the corrosion and expansion of reinforced concrete.At present,the research of reinforced concrete rust expansion is mostly carried out at the macro level,in the process of the meso-level research,the reinforced concrete is regarded as a heterogeneous material composed of reinforcing steel,aggregate,mortar and the interface transition zone(ITZ)between reinforcing steel,aggregate and mortar.Through the macro-level accelerated corrosion test of reinforced concrete and the micro-level numerical simulation analysis,the relevant phenomena and conclusions are finally obtained.Starting from the meso-level,the concentration distribution of chloride after diffusion in concrete is fitted by MATLAB mathematical programming platform;then the accelerated corrosion expansion test is carried out on some characteristic reinforced concrete specimens;then,based on the theory of random aggregate model,the polygon aggregate model considering the area ratio increase factor is established by using Monte Carlo method with the help of MATLAB programming platform.Finally,with the help of ABAQUS finite element numerical simulation software,the force displacement and equivalent force of the model are applied to simulate the expansion of rust expansion damage of specimens,and on this basis,the influence of the thickness of protective layer on the expansion of damage of specimens is simulated.It can be used to determine that: MATLAB can fit the process of chloride diffusion in concrete,and found that the chloride concentration distribution around the reinforcement is nonuniform;from the view of reinforced concrete corrosion expansion process,when the reinforcement is located in the middle of the concrete,the difference between the cracking time and the ultimate failure time of the outer end of the concrete is greater than when the reinforcement is located in the corner;According to the results of slice damage,the damage distribution of concrete with steel bar in the middle is approximately in the shape of “?”,while the damage distribution of concrete with steel bar in the corner is approximately in the shape of “×”,and the measured radius of steel bar corroded indicates that the corrosion result of steel bar is non-uniform.The results of finite element numerical simulation show that the loading mode of equivalent force is better than that of forced displacement.Furthermore,the effect of protective layer thickness on concrete damage simulated by equivalent force loading mode shows that the protective layer thickness of steel bar has a great influence on the damage degree and damage morphology of specimens.