Study On Damage Effact Of Concrete Under The Coupling Of Chloride Salt Penetration And Diffusion

At present,seawater and saline soil are the two main environments for corrosion of concrete piers with chloride salts.The corrosion mode is mainly based on adsorption,diffusion and infiltration of capillary pores,and corrosion is carried out under the co-coupling of adsorption,diffusion and permeation of capillary pores.Therefore,the study of the damage of concrete under the coupling of chloride salt diffusion and diffusion is significant for the safe use of bridges.significance.In this paper,the combination of laboratory test,theoretical analysis and numerical calculation is used to simulate the erosion behavior of concrete under the coupling of chloride salt diffusion and chloride salt penetration and diffusion in salt solution environment and saline soil environment,and analyze its physical,mechanical and permeability properties.,get the following main conclusions:(1)Corrosion test device developed by ourselves was used to corrode the cylindrical concrete sample,and the diffusion coefficient of chloride ion was calculated by the corresponding formula.The results showed that: 1 salt solution corrosion environment> saline soil corrosion environment;9.30%>0.93%>0.10%;3osmotic diffusion coupling erosion method> diffusion erosion method..(2)According to Fick's second law,the comsol numerical simulation software was used to establish a numerical model for the diffusion of chloride ions in the process of corrosion of concrete with chloride salt under the three variables of corrosion environment,chloride concentration and erosion mode.It is revealed that with the increase of corrosion time,the chloride ion concentration in concrete shows a gradual increase and the diffusion coefficient gradually decreases,which further verifies the conclusion of the test.(3)Based on laboratory tests,the mechanical properties of concrete after erosion were tested.The test results show that the uniaxial compressive strength and splitting tensile strength of concrete after erosion show a trend of increasing first and then decreasing,and 75 d is the turning poin of the intensity change ot.(4)According to the theory of solid mechanics,a numerical model of post-corrosion concrete strength under three variables was established by means of comsol numerical simulation software.It reveals the law that the strength first increases and then decreases with the increase of corrosion time.The conclusion ofthe test is verified and provides a theoretical basis for guiding practical engineering applications.(5)The damage degree is defined by the compressive strength as the index.The change of the damage degree with time under the influence of three kinds of variables shows a trend of increasing first and then decreasing.The damage degree and time under the corrosive environment and erosion mode are cubic functions.The concentration of salt solution and the damage degree show a quadratic function relationship.Combined with the influence of chloride concentration on the diffusion coefficient during the corrosion process,the chloride salt is changed under the concentration gradient to change the diffusion coefficient of chloride ion inside the concrete,and the diffusion coefficient changes.Then the corrosion degree of the concrete sample is affected with time,and the damage mechanism of the concrete whose uniaxial compressive strength changes is caused.