"This study aims to: (1) explore, develop, calibrate and validate Fe-C coated, long period fiber grating (LPFG) sensors for short-term mass loss measurement of the Fe-C coating; (2) develop, calibrate, and validate steel tube-encapsulated, fiber optic probes and LPFG sensors for long-term mass loss detection of the steel tube; (3) correlate the corrosion process of packaging metal materials with that of steel bars in direct contact with the packaged probe or sensor except for a thin insulation tape; and (4) apply both types of corrosion sensors into reinforced concrete (RC) structures for reinforcing bar corrosion monitoring and structural condition assessment. For short-term monitoring, the corrosion mechanism of the Fe-C coating and the corrosion sensitivity of the Fe-C coated LPFG were investigated and characterized in 3.5 wt. % NaCl solution. For long-term detection, the probe or sensor was used to measure the pitting corrosion growth of steel tubes in simulated concrete pore solution. To validate them in an application setting, two types of LPFG corrosion sensors were embedded in three RC beams under accelerated corrosion test. The resonant wavelength of a Fe-C coated LPFG sensor can be linearly related to the mass loss of Fe-C coating up to 60~90%. When tested in 3.5wt. % NaCl solution, the LPFG sensor coated with an 8~20 μm thick Fe-C layer has a sensitivity of 0.15~0.23 nm/1% Fe-C mass loss. This sensitivity is translated into approximately 1300 nm/g in mass loss of reinforcing steel bars. In RC beam applications, the resonant wavelength of an Fe-C coated LPFG sensor is reduced by 0.49 nm/hour when installed along a steel bar under accelerated corrosion conditions and 0.95 nm/day when installed near the bottom surface of a beam under natural corrosion condition. The corrosion penetration rate through the wall of a steel tube is approximately 8.6 μm/day"--Abstract, page iii.
Yan, Guirong Grace
Civil, Architectural and Environmental Engineering
Ph. D. in Civil Engineering
National Science Foundation (U.S.)
Missouri University of Science and Technology
xii, 108 pages
© 2017 Yizheng Chen, All rights reserved.
Dissertation - Open Access
Electronic OCLC #
Chen, Yizheng, "Long-period fiber grating corrosion sensors for life-cycle monitoring and assessment of reinforced concrete structures" (2017). Doctoral Dissertations. 2740.