Sensors systems, especially fibre optic sensors in structural monitoring applications in concrete: An overview

Reinforced concrete is the most popular construction material in the world due to its flexibility to make different complicated shapes, yet providing strength, long service life and structural integrity. However, a major issue for reinforced concrete structures is the corrosion of the reinforcement bars (rebars) when exposed to aggressive environmental conditions, such as those in marine or urban environments. The corrosion is normally caused by the ingress of chlorides, as in the case of marine environment, or carbon dioxide, as in the case of urban environment; the latter causes a reduction in the alkalinity of concrete through a process called carbonation and steel loses the protection provided by the concrete. Corrosion products (rust) occupy many times the volume of the original steel and as a consequence the integrity of the structure is severely compromised and occasionally leads to a catastrophic structural failure. Therefore, it is highly desirable to obtain information about factors which initiate the corrosion and the rate of corrosion once it has already started, both of which will help civil engineers to manage their reinforced concrete structures in a cost-effective manner.