Research On Transport Of Chloride Ion In Concrete Under The Sustained Compressive Load

The study on the transport of chloride ion in concrete under the sustained compressive load is the key in the durability study of concrete structures under marine environment.Aiming at analysis of transport of chloride ion in concrete under the sustained compressive load in this research: through theoretical analysis,numerical simulation and experimental verification of combination,considering the load and other factors on the effect of chloride ion transport process in concrete,put forward by a numerical model for predicting the chloride erosion life of concrete structure,and analysis the chloride transport process of LNG prestressed concrete outer tank under a long-term compressive load.The specific content is described as follows:1.From the micro perspective,the cement hydration model of Krstulovic-Dabic as the foundation,considering the influence of cement hydration and chloride combined salt with continuous filling effect on diffusion coefficient of chloride ions,put forward a chloride ion transport model in concrete;and based on the verification of the model,the influence of temperature,humidity,ash water ratio,aggregate and other parameters on the transmission process of chloride ion in concrete is discussed.2.From the two aspects of low grade and high grade load analysis of sustained compressive load effect on transmission of chloride ion in concrete;through multiphase sphere model,creep prediction formula and damage mechanics theory,the establishment of the transport of chloride ions in various stages of the numerical model,and compared with experimental results in the literature,to verify the accuracy the numerical model.3.In a large LNG storage tank prestressed concrete outer tank as the research object,using COMSOL finite element software to establish numerical model of LNG tank and the outer tank;considering the temperature,humidity,water cement ratio,aggregate content and concrete creep effect,analyzes the external environment and the sustained effect caused by ballast tank tank concrete the chloride ion distribution characteristics,determine the key parts and maintenance tank outside the tank durability design;and discusses the influence of water cement ratio,the thickness of the protective layer and curing period on the transmission of chloride ion of LNG prestressed concrete outer tank ballast in the long-term bear;finally,put forward the LNG tank tank based on Chlorine Ion Erosion Durability Design.The results show that the water cement ratio,temperature and humidity of chloride ions in concrete influence the apparent diffusion coefficient was positively correlated negatively correlated with aggregate content;in the low level of pressure load,stress on chloride ion effects of apparent diffusion coefficient was negatively correlated;at a high level of pressure load,stress on effect of apparent chloride diffusion coefficient was positively correlated;the first tank pouring LNG prestressed concrete wall with steel,more prone to corrosion,increase the thickness of protective layer recommend a local way of improving the durability of the first tank pouring belt,the recommended thickness of the protective layer by 55 mm.