Research On Corrosion Of Epoxy Coated Steel Reinforcement In Marine Engineering Concrete Structures

The corrosion of reinforcement in Marine engineering concrete structures has an important effect on the durability of concrete structures.As one of the main measures to prevent reinforcement corrosion in Marine concrete structures,there are still some problems to be solved in practical engineering application of epoxy coated reinforcement.According to the domestic and foreign research results of laboratory tests,when epoxy coated steel bars are transported,stacked,processed,tied and tampered,the coating is vulnerable to local damage,forming a small anode area in the locally damaged part,and other intact parts as a large cathode area,which may accelerate the macrobattery corrosion(pit corrosion)of steel bars in the damaged part.That is to say,the epoxy coated steel bars with local damage can not improve the durability of concrete structures,but may accelerate the local corrosion of steel bars,resulting in the accelerated decline of durability of concrete structures.Therefore,the research on the non-destructive identification of coating damage and corrosion behavior mechanism of in-service epoxy steel bars is of great significance to the bearing capacity,later maintenance and service life prediction of marine concrete structures.The main contents of this paper are as follows:(1)Based on the field investigation of the surface damage of epoxy steel bars in concrete structures under marine environment,the causes of the surface coating damage of steel bars are analyzed,and the corrosion mechanism is analyzed.The corrosion of steel bars is detected and protected by the corrosion mechanism.(2)The electrochemical behavior of epoxy steel coating with damage of 0 cm,2 cm and 4 cm was tested by open-circuit potential and electrochemical impedance spectroscopy(EIS).The change process of open-circuit potential and impedance spectroscopy under each degree of damage was analyzed and compared,so as to qualitatively judge whether the epoxy coating has local damage or not.(3)Based on the self-designed experimental device,the electro-accelerated corrosion of reinforced concrete specimens was carried out.The corrosion current density,corrosion potential and polarization resistance of epoxy steel bars with 0 cm,2 cm and 4 cm coating damage were measured by CS354 multi-channel electrochemical workstation.The corrosion rate was calculated by linear polarization method,andthe electrochemical behavior of steel bars in the corrosion process was also studied.(4)Abaqus was used to simulate the corrosion behavior of Epoxy Steel Coating under local damage of 2cm and 4cm,and the expansion displacement amount under different accelerated corrosion time was calculated.The results calculated by this method were compared with those calculated by electrochemical workstation.