Durability tests of a fiber optic corrosion sensor

• Published in: Sensors (Basel, Switzerland) Vol. 12; no. 3; pp. 3656 - 3668
• Main Authors: Wan, Kai Tai, Leung, Christopher K Y
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.03.2012; Molecular Diversity Preservation International (MDPI)
• Subjects: chemical degradation; Chloride; Concrete; Corrosion; corrosion sensor; Degradation; Durability; fiber optic; Fiber Optic Technology; Fiber optics; freeze-thaw cycling; Freeze-thaw durability; Freezing; Humidity; Inorganic Chemicals - chemistry; Light; Marine environments; Measurement techniques; Optical Fibers; optical time domain reflectometer; OTDR; Oxidation-Reduction; Reinforced concrete; Sensors; sputtering; Thin films; Hong Kong China; China; corrosion sensor; fiber optic; optical time domain reflectometer; OTDR; chemical degradation; sputtering; freeze-thaw cycling
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s120303656

Steel corrosion is a major cause of degradation in reinforced concrete structures, and there is a need to develop cost-effective methods to detect the initiation of corrosion in such structures. This paper presents a low cost, easy to use fiber optic corrosion sensor for practical application. Thin iron film is deposited on the end surface of a cleaved optical fiber by sputtering. When light is sent into the fiber, most of it is reflected by the coating. If the surrounding environment is corrosive, the film is corroded and the intensity of the reflected signal drops significantly. In previous work, the sensing principle was verified by various experiments in laboratory and a packaging method was introduced. In this paper, the method of multiplexing several sensors by optical time domain reflectometer (OTDR) and optical splitter is introduced, together with the interpretation of OTDR results. The practical applicability of the proposed sensors is demonstrated in a three-year field trial with the sensors installed in an aggressive marine environment. The durability of the sensor against chemical degradation and physical degradation is also verified by accelerated life test and freeze-thaw cycling test, respectively.