Reseach On Durability Of Concrete Stuctures Exposed To Chloride Enviroment

Reinforced concrete structure is the main structure form in current construction; therefore,it is of strong practical significance for the durability study of concrete.Steel corrosion is the main effect factor for the concrete durability, while the chloride ion is the main reason that leads to reinforcement corrosion, in the oceans,de-icing salt and other chloride intrusion environment,the damage of the concrete structure caused by the chloride ion intrusion is the most serious.In this paper, comprehensivly analysing relevant research results at home and abroad, at the same time, using the method comprehensed theoretical analysis with the measured data analysis, which are applied in durability study of the concrete structures under the chloride ion erosion environment, then the main research contents are as follows:First, in this paper, based on the Fick's second diffusion law, and considered that the proliferation of chloride ions are influenced by many factors in concrete structure under different erosion circumstances, then the improved chloride ion diffusion model, integrating time-dependent of the chloride ions diffusion coefficient and other factors affect, is established, while the selection and determine of model parameters are discussed in-depth.the caculated date of the improved model and the Measured data are compared for analysis.Second, the concrete's chloride ion diffusion coefficient and surface chloride ion's concentration change with time, which show that it is difficult to gain the analytical solution of the Cl-diffusion process from the Fick's second diffusion law. Therefore, the Diffusion module of the COMSLOL finite element software is used to carry out numerical simulation for diffusion process of chloride ions, and the outcome forecasted is compared with the test results, which show that the method is effective for diffusion analysis of the chloride ion.Later, in the actual environment, the proliferation of chloride ions is affected by the time factor and the different chlorine erosion environment factors, then chloride ion diffusion of the concrete is done with numerical simulation in different erosion environment, different water-cement ratio and different age respectively. The results show that the selection of the time-dependent index m is crucial for the durability analysis of the structure under the chloride ion erosion circumstance, which lead to a new forecasting method to analys, the structure of the chloride ion concentration of the concrete structure under coastal and de-icing salt circumstances. Finally, comprehensed the contents of the above and considered the affect of the different factors for the durability of concrete environments, the design methods and design thinking of the durability are proposed for planed structure in the erosion environment of chloride ions, which improve the design theory of the concrete structure's durability.