Simulation Test Study On Chloride Ion Transport Law In Marine Concrete

The reinforced concrete structure is widely used for the port,cross-sea bridges and other infrastructures,whose vertical main bearing components,like reinforced concrete columns,piers and so on,are suffered the seawater erosion,deep sea pressure,and marine aggressive media and other complex effects.Chloride ion,which is gradually accumulating on the surface of the re-bar by concrete porosity,is a typical representative of corrosive media in seawater.When the chloride ion concentration reaches the threshold on the surface,the re-bar starts to rust,which significantly reduces the overall performance of reinforced concrete structure.It is of great social and economic significance to study the transport law and mechanism of chloride ion in concrete under the marine environment,and it also can contribute to the scientifically evaluating the service performance and life of marine concrete structure.Based on the self-developed devices,taking the vertical component of marine concrete as the main object,this paper separately studied the chloride ion tests of penetration law with concrete in the marine environment and penetration mechanism for concrete under the pressured deep-sea.The main research work and achievements were as follows.1.The basic structure and principles of the two self-developed devices,such as the " marine environment simulation device" and " pressure deterioration vessel",were briefly introduced in the paper,which were used to simulate the ocean environment and deep-sea pressure respectively.2.The paper discussed the penetration law of the chloride ion in the shallow sea.The influencing factors such as time,partition and solution concentration were respectively considered.At the same time,the characteristics and differences of the infiltration in different zones were analyzed,and the model of chloride ion penetration was also established.The following conclusion can be drawn:(1)By comparing the chloride ion concentration in different zones,the relationship of the speed of the permeability was acquired.The order(from fast to slow for sorting)issubmerged zone,tidal zone tend to submerged zone,tidal zone tend to atmospheric zone,atmospheric zone;(2)Considering the different erosion with sea water or different concentration of saline water,the chloride ion concentration and ion ratio in the solution all affected the penetration,which was the higher the chloride ion concentration or ratio,the greater the penetration result;(3)By comparing the data of motion and static state,it was concluded that moving water can accelerate the penetration of chloride ions;(4)The experimental data,which fitted with theoretical model,obeyed Fick's second law.3.The concrete in the deep sea was studied by using pressure deterioration vessel,and the results showed that:(1)The total chloride ion,free chloride ion and bounding chloride concentration all increased with time,decreased with depth,and the permeation rule of total chloride ion obeyed Fick's second law;(2)By making the samples be saturated with chloride ion in the given solution,the different water-cement ratio was considered.And the relationship between the chloride ion concentration in the solution and the chloride ion concentration in the concrete was established,which providing a reference for surface chloride ion concentration;(3)Based on the principle of the full water test method and using the XCT method to prove the sample be filled of water,the permeable porosity was measured by the new method,which comparing with the porosity measured by mercury porosimeter,nitrogen adsorption,XCT's analysis.