Experimental Study And Correction Model Of Chloride Ion Corrosion Of High Performance Concrete

Concrete is served as one of the most important materials in engineering industry,and the durability is directly related to the security and economy benefit.As for concrete structure in marine environment,there are plenty of security incidents of concrete structure damage caused by chloride corrosion each year.Chloride ion can easily penetrate into concrete structure through seawater owe to the rich content of chloride ion in seawater.Large accumulation of chloride ion will cause reinforcement corrosion and hence affect the stability and durability.As a commonly used quality concrete material in engineering construction,study on chloride ion corrosion of high performance concrete should arouse attention in order to avoid the occurrence of accident and maintain the durability of concrete structure.Therefore,based on the conclusion of existed research findings,the thesis conduct experiment study and theory analysis on the chloride ion mechanism of high performance concrete.The main work are as follows:(1)Existed chloride ion diffusion mechanism,chloride ion diffusion model and chloride corrosion test methods are both summarized,and characteristic of each chloride ion corrosion methods are compared and analyzed,selecting the naturally immersion method as the most suitable test method.(2)Mix proportion of high performance concrete is designed according to regulatory requirements,and a group of high performance concrete test block was fabricated.Naturally immersion method was selected for chloride corrosion test for high performance concrete.Concrete powder samples by drilling is tested by RCT machine and the test data was obtained.(3)The chloride ion profiles of high performance concrete with different strength was explored through fitting analysis of test data.On the basis of Fick's second law,the diffusion coefficient of each concrete block was obtained through Matlab fitting.The differences of chloride profiles and diffusion coefficient between the ordinary concrete and high performance concrete were compared.For high performance concrete,the chloride ion diffusion coefficient was proved to be in good agreement with water binder ratio and compressive strength.(4)The correction coefficient K for chloride ion diffusion coefficient of high performance concrete was put up.The concrete block of OC30,OC40 and OC50 were set as reference concrete,compared with high performance concrete on chloride ion diffusion coefficient.The values of K of high performance concrete with different strength were obtained on the condition of different reference concrete.the suggested value of K is about 0.2-0.35 times of ordinary concrete and can be applied to predict the chloride ion diffusion coefficient.(5)For the chloride ion corrosion environment,based on the Fick's second law,the influence factors of chloride ion diffusion for high performance concrete were analyzed.The revised model of chloride ion diffusion considering temperature,humidity,binding capacity and so on was established and its parameters values were given.Besides,the revised model was well verified through test data by Matlab program.