Experimental Study On Chloride Ion Penetration In Concrete Subjected To Fatigue Load Coupling With Chloride

Reinforced concrete structures are widely used in civil engineering due to their excellent mechanical properties and durability.However,with the complications of concrete service environments,the mechanical properties and durability performance of reinforced concrete structures are gradually degraded over time.The main reason why the service life of the structure does not reach the expected target is that the reinforcing steel is gradually rusted during service,and the chloride ion is the root cause of the accelerated corrosion of the steel bar.Therefore,the study of the transport law of chloride ions in concrete is important for the durability evaluation.The concrete will be subject to fatigue load in the actual service environment.The internal pores and cracks will be changed.And then the chloride ion permeability of the concrete will also be affected.At present,the penetration of chloride ions in concrete under load is relatively common.However,studies of chloride ion permeability under the coupled effects of fatigue loading and chloride salt is less,and the coupling condition is more corrected with the real service environment of concrete.In this paper,the permeability of the concrete under different stress levels was studied through the self-designed experimental device.The work and the research content is as follows:1).Through the coupling device designed by the self-designed test device to achieve concrete fatigue damage and chloride salt erosion,studying the damage mechanism of the load on the concrete and exploring the effect of load on the permeability of chloride ions in concrete.2).Based on CT,the changes of CT pixels and CT grayscale pixels were used to study the effect of fatigue loading on concrete damage.The development law of cracks was analyzed.The mechanism of fatigue damage to concrete was revealed.And the correlation between fatigue load and damage was established.3).Based on Fick’s second law,MATLAB software was used to fit the apparent chloride ion concentration and the chloride ion diffusion coefficient,and the distribution law of chlorine ion concentration was analyzed,and the variation characteristics of the chloride ion diffusion coefficient were compared with the chloride ion concentration and diffusion at different stress levels.The law of coefficient changes,the relationship between the stress level and the chloride diffusion coefficient is studied.The correlation between the stress level and the chloride diffusion coefficient is established.4).The correlation between the established fatigue load and damage,and the correlation between fatigue load and chloride ion diffusion coefficient is analyzed.Exploring the relationship between the damage and the chloride ion diffusion coefficient from the microscopic perspective,revealing the mechanism of the impact of chloride on the transmission of damage,and establishing the correlation between the damage performance and chloride ion penetration.5).Summaring the full text of the research content and the conclusion,and puts forward the shortcomings of existing studies and problems that need further study.