Theoretical Study On Chloride Ion Transport Mechanism In Concrete

Along with China’s sustained economic growth and opening to the outside world continue to deepen reform,demand for shipping market is becoming more and more big.In order to adapt to the strong demand of the market and promote the steady development of the national economy,a large number of quay berths have been built in China’s coastal ports.At the same time,China has also built a large number of cross-sea Bridges and coastal buildings.Most of these projects belong to reinforced concrete structures.Seawater usually contains 3% salt,mainly chlorine salt.The content of chloride ion in seawater is about 19g/L.Meanwhile,sea breeze and sea fog also contain chlorine salt.Therefore,due to long-term exposure to the Marine chloride erosion environment,the harbour project,cross-sea bridge,coastal buildings and other concrete deterioration,resulting in a considerable part of the project can not reach the predetermined design life and premature damage.The research on the durability of concrete structures in Marine environment has important engineering significance.Based on the second law of traditional Fick,this paper optimizes the traditional model to better analyze the diffusion mechanism of chloride:1.Based on the traditional Fick second law,the relationship between diffusion coefficient,time and temperature is considered by modifying the diffusion coefficient.The Fourier transform is used to solve it.The effects of age and ambient temperature on the diffusion of chloride ions in concrete are analyzed respectively.Studies have shown that different ages and ambient temperatures have certain effects on the diffusion of chloride ions.2.According to the classical Fick second law,fractional order is introduced,and the semi-analytical solution of the diffusion equation is obtained by using the Laplace transform method and Crump inversion method.The influence of different fractional order on chloride ion diffusion in concrete is analyzed by using the semi-analytical solution.The results show that different fractional orders have important effects on chloride diffusion.