Numerical Model Analysis Of Ion Migration In Concrete In Saline Soil

Ion erosion in saline soil is the main cause of durability failure of concrete structures.Chloride migration model in concrete is analyzed based on diffusion,binding,electric field and capillarity adsorption.The sulfate ion migration model in concrete considering the concrete compaction was established.Based on crack concrete,the chloride ion migration model in cracked concrete is established,and the relationship between crack width,crack depth and protective layer thickness and crack concrete service life is analyzed.Analysis of the distribution of chloride ions in concrete,improve the strength of concrete,increasing the concrete cover thickness,adding fly ash and concrete surface coating effect on delaying the invasion of chloride in concrete.The main results of the research are as follows:(1)Based on the diffusion,binding,electric field and capillary adsorption of chloride ion in concrete,the influence of different mechanisms on chloride migration in concrete is analyzed.The influence of different initial pore saturation of concrete,different chloride ion concentration on concrete boundary,the action of potential field and the effect of binding on chloride ion distribution in concrete were analyzed.Based on the Fick diffusion equation,a chloride ion migration model considering the binding and electric field is established.Through the analysis of the related experimental results,the correctness of the model is verified.(2)In the process of concrete compaction caused by sulfate attack,the migration model of sulfate ion in concrete is established,which considers the concrete compacting process.The influence of concrete compaction on the distribution of sulfate ion and chloride ion in concrete was studied.The failure law of concrete subjected to sulfate attack was analyzed.(3)The chloride ion migration in concrete with a single crack is studied,and the coupling model combined diffusion,binding,and electric field is established,the crack concrete service life is predicted.The distribution law of chloride ion in concrete with a single crack along with time and space,the influence of different thickness and depth of crack on chloride ion migration law are analyzed.The relationship between crack width,crack depth,protective layer thickness and service life of crack concrete was established.(4)From the saline soil in Nantong coastal areas,the distribution of chloride ion in concrete was simulated.The effects of increasing of the concrete protective cover thickness,increasing the concrete strength grade,adding fly ash material and anti-corrosion coating on concrete surface to retard the ingress of chloride ion in concrete were studied.