Environmental-friendly Migrating Corrosion Inhibitor And Effect On Corrosion Behavior Of Steel In Chloride-contaminated Concrete

At present,the migration inhibitor(MCI)has become an effective way to improve the durability of concrete.In this paper,based on the concept of environmental friendly products,a kind of green water-based migration inhibitor(PCI-2016)was developed.The effect of adding PCI-2016 on the corrosion resistance of the working electrode in 1% salt solution was tested by electrochemical working system,the results show that PCI-2016 has excellent ability to inhibit the corrosion of steel bars.SEM-EDS and AFM-XPS were used to observe and analyze the surface of the two groups of steel disc with and without PCI-2016.The results show that the steel disc is not corrosion by adding PCI-2016,the microscopic surface topography can be clearly observed PCI-2016 molecules to form a dense protective film on the surface of the steel sheet,without adding PCI-2016 caused severe corrosion.The stability of PCI-2016 film on the surface of steel was described by dynamic potential scanning and Temkin adsorption equation,the results show that the adsorption behavior of PCI-2016 on the surface of steel is stable.The critical repair concentration of PCI-2016 was studied,and the relationship equation between chloride concentration and PCI-2016 concentration was obtained.A simplified mathematical model of surface coated MCI in concrete was studied.The low field NMR technique was used to validate the short term liquid phase transport model,the results show that the short term liquid phase transport model can be used to analyze the mass transfer process of the non reactive MCI in saturated condition.Based on Fick’s law,the establishment of long term gas phase mass transfer model was studied,the concentration of nitrogen in the interface region of the steel bar was measured by experiment to verify the applicability of the model.The relationship between the concentration of nitrogen,the content of water soluble chloride ion and the corrosion current density of steel bar in concrete was analyzed by multiple linear regression method.The results show that the determination coefficient is 0.9390,which shows a high degree of correlation.The effect of PCI-2016 coating on the compressive strength of the newly formedstructure was studied.The diffusion coefficient of chloride ions in 3 water binder ratio concrete structures after two layers of PCI-2016 was tested,which was reduced to about 85.53%,79.39% and 60.59%,respectively;The chloride diffusion coefficients of 3 water binder ratio concrete structures with two layers of PCI-2016 and one layer of waterproof agent were tested,which were reduced to about 35.22%,29.09% and23.53%,respectively.Steel bars in mortar specimens were removed and analyzed by XPS element,the results show that PCI-2016 diffuses through the concrete protective layer to the surface of the reinforcing steel and the chlorine atoms are excluded.The change of corrosion current density of steel bar working electrode after four cycles of soaking and drying was studied by LPR electrochemical test,three dimensional scanning technology is used to scan and reconstruct the steel bar,the statistical analysis of cross section area of corroded steel bars is carried out by means of mathematical statistics.The results show that the protective effect is obvious after two layers of PCI-2016 and a layer of waterproof agent are applied on the concrete surface.