Reinforced Concrete Corrosion: EMI Process Monitoring Techniques

Reinforced concrete is major construction material for civil infrastructure, and corrosion of concrete reinforcement is one of the main factors leading to premature deterioration of concrete structures worldwide.

The risk of corrosion damage increases with the age of the structure, particularly when the original design service life has lapsed. Therefore, the detection of steel corrosion at the early stages is very important to ensure the safety and prevention of structural damage. In addition, an extensive monitoring system for corrosion can help estimate the remaining service life of the structures.

The corrosion of steel reinforcement in concrete often leads to huge unbudgeted expenses for maintaining, monitoring, and renovating an infrastructure. This is mainly due to the presence of salts or chemical chlorides that pose a danger to the concrete structures. The determination of the existence of these corrosive salts is vital for defining the service life of the concrete. This research looked at developing an electromagnetic induction (EMI) sensor for the detection of corrosive salts. The first design adopted a single-loop coil (SLC) concept, and the second was based on a multiple-loop coil (MLC) one using copper wire. Tests were conducted on these two techniques, and with the results obtained, the latter seemed more promising; thus, a prototype sensor was developed using the MLC concept. As this new prototype sensor was able to detect the manifestation of chemical contents in a concrete structure, it could be used as a non-destructive evaluation (NDE) technique for the detection of corrosive chemicals in concrete and has the further possibility of detecting corrosion in concrete.