Abstract
Corrosion of steel rebars in reinforced concrete impacts structural integrity of the infrastructure. While several Non-Destructive Testing and Evaluation (NDT&E) techniques exist for corrosion monitoring in structures, there is a need for cost-effective solution for early detection of sub-surface corrosion of rebars in civil infrastructure. Here we present a low-cost corrosion sensing system based on pulsed eddy current detection using anisotropic magnetoresistive (AMR) sensor to detect the corrosion in steel reinforcing bars. A novel probe with large figure of merit ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$21.62\times6$ </tex-math></inline-formula> m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{T}^{-1}$ </tex-math></inline-formula> ) is presented, that can detect corrosion in 20 mm diameter rebars at lift-off distances as high as 55 mm with low excitation current of 0.2 A. The sensitivity is enhanced by using area under the curve of various segments of the time-domain sensor output as features. Optimal feature selection and dimensionality reduction, as well as quantitative estimation of extent of corrosion are demonstrated using principal component analysis.
Published Version
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