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Corrosion Monitoring of Steel Rebar by Long-Period Fiber Grating Sensors Coated With a Thin Fe-C Layer

In this study, the corrosion of steel rebar is monitored by distributed optical fiber gratings sensors deployed in parallel with the rebar. Long-period fiber gratings (LPFG) are coated with a thin Fe-C layer so that the corrosion of the Fe-C coating is correlated with the rebar corrosion. Light can propagate through the core and cladding of a LPFG sensor. The cladding mode of light propagation is significantly affected by the environmental refractive index of the sensor, resulting in a potential change of wavelength over time. The wavelength change is related to the degree of corrosion through laboratory calibration tests by placing both the LPFG and a reinforcing steel bar in the same corrosion environment. The wavelength change and the corrosion degree are quantified by an optical spectrum analyzer (OSA) and an electrochemical impedance spectroscope (EIS), respectively. Test results indicated that the Fe-C coated LPFG sensor can be applied to successfully monitor the onset of corrosion along the length of steel rebar. In practical applications, the change in wavelength of the LPFG sensor is first measured with the OSA and then converted to the degree of corrosion in iron coating through their calibrated relation. For long-term monitoring, LPFG sensors may be coated with a thin layer of stainless steel that can be corroded slowly over time and better correlated with the corrosion of the steel rebar.

1. Ghods P, Isgor OB, McRae G, Miller T. “The effect of concrete pore solution composition on the quality of passive oxide films on black steel reinforcement.” Cement and Concrete Composites, 31(1):2-11, 2009. 2. Feng X, Zuo Y, Tang Y, Zhao X, Lu X. “The degradation of passive film on carbon steel in concrete pore solution under compressive and tensile stresses.” Electrochimica Acta, 58:258-263, 2011. 3. Yu H, Chiang KTK, Yang L. “Threshold chloride level and characteristics of reinforcement corrosion initiation in simulated concrete pore solutions.” Construction and Building Materials, 26(1):723-729, 2012. 4. Bohni H. Corrosion in Reinforced Concrete Structures. Cambridge, UK: Woodhead Publishing, 2005. 5. Zhang R, Castel A, Francois R. “Concrete cover cracking with reinforcement corrosion of RC beam during chloride-induced corrosion process.” Cement and Concrete Research, 40(3):415-425, 2010. 6. Shannag MJ, Al-Ateek SA. “Flexural behavior of strengthened concrete beams with corroding reinforcement.” Construction and Building Materials, 20(9):834-840, 2006. 7. Yi W, Kunnath SK, Sun X, Shi C, Tang F. “Fatigue behavior of reinforced concrete beams with corroded steel reinforcement.” ACI Structural Journal, 107(5):526-533, 2010. 8. Xia J, Jin W, Li L. “Shear performance of reinforced concrete beams with corroded stirrups in chloride environment.” Corrosion Science, 53(5):1794-1805, 2011. 67 9. ASTM. Standard Test Method for Corrosion Potentials of Uncoated Reinforcing Steel in Concrete. American Society of Testing Methods (ASTM), C876-09, 2009. 10. Song G, “Theoretical analysis of the measurement of polarization resistance in reinforced concrete.” Cement and Concrete Composites, 22 (6): 407-415, 2000. 11. Sagues AA, Kranc SC, Moreno EI, “Evaluation of electrochemical impedance with constant phase angle components from the galvanostatic step response of steel in concrete.” Electrochimica Acta, 41(7-8):1239-1243, 1996. 12. Hu W., Cai H, Yang M, Tong X, Zhou C, Chen W. “Fe-C-coated fibre bragg grating sensor for steel corrosion monitoring.” Corrosion Science, 53(5):1933-1938, 2011. 13. Majumder M, Gangopadhyay T, Chakraborty A, Dasgupta K, Bhattacharya D. “Fiber bragg gratings in structural health monitoring-present status and applications.” Sensors and Actuators A: Physical, 147(1): 150- 164, 2008. 14. Dong S, Liao Y, Tian Q, Luo Y, Qiu Z, Song S. “Optical and electrochemical measurements for optical fibre corrosion sensing techniques.” Corrosion Science, 48 (7) 1746-1756, 2006. 15. Li XM, Chen. WM, Huang ZQ, Huang SL, Bennett KD. “Fiber optic corrosion sensor fabricated electrochemical method.” Smart Structures and Materials, 3330 126-133, 1998.
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