Practical application of an optical fiber sensor for corrosion in concrete structures

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 a structure. This paper presents the development of a new corrosion sensor for concrete structures based on fiber optics. An iron coating is sputtered on the end of a cleaved optical fiber, which is then packaged and placed inside a concrete structure. Light is sent to the fiber end and the reflected power is monitored. Once the environment becomes corrosive, due to chloride penetration or carbonation, the iron coating is removed, and the reflected power shows a significant drop. The present work focuses on the design of a corrosion sensor that can be retrofitted to an existing structure. Details on sensor design, fabrication, installation and data acquisition will be provided. Results of a field trial are presented to demonstrate the applicability of the corrosion sensor under aggressive marine environment.