Published 15 April 2014, SPIE Newsroom. DOI: 10.1117/2.1201404.005448

Reinforced concrete is subject to corrosion, which ultimately leads to total failure of the structure. In the first stage, elements such as moisture and chloride penetrate the concrete. Upon reaching the reinforcing steel bars, high concentrations of these elements attack the passive layer of hydrated iron oxide that protects the bars against corrosion. Rust begins to form, ferric compounds convert to ferrous, and the volume of the structure expands by five to 10 times. Immense pressure starts to build, causing more cracks. If this process continues unchecked, the structure eventually fails.

Therefore, corrosion monitoring is essential to preserve the life of civil structures, and early diagnosis and monitoring of seemingly healthy concrete enables pre-emptive corrosion control measures. However, identifying the specific causes of corrosion can be challenging, since there are several causes.1 Deterioration and cracks can be the result of poor concrete mix, poor workmanship, inadequate design, shrinkage, chemical and environmental attack, physical or mechanical damage, and corrosion of the reinforcing steel (RS). Here, we present a road map for developing a suite of sensors and an associated system to detect corrosion in the RS and the degree of damage at a certain moment in time.2 Our proposed system enables high resolution and would offer an accurate estimate of the remaining life in a concrete structure.

Read the full article at http://spie.org/x107489.xml.