Phase sensitive detection of extent of corrosion in steel reinforcing bars using eddy currents

TL;DR

This paper introduces a low-cost, phase-sensitive eddy current detection method using an AMR sensor to non-destructively assess corrosion levels in steel rebars, promising improved maintenance and durability of RCC structures.

Contribution

It presents a novel, cost-effective sensing platform employing phase-sensitive detection with an AMR sensor for corrosion assessment in steel rebars.

Findings

Sensor can distinguish varying corrosion levels

Phase shift correlates with surface conductivity

Potential for industrial NDT applications

Abstract

Corrosion of steel bars in reinforced cement concrete (RCC) structures leads to premature deterioration and increase in life cycle maintenance costs. Non-destructive testing (NDT) of incipient corrosion has been an impending task in this domain. We present a low cost sensing platform based on eddy current detection using anisotropic magnetoresistive (AMR) sensor to measure the extent of corrosion in steel reinforcing bars (rebars). The scheme employs phase-sensitive detection, wherein the phase shift in the sensor output (proportional to surface conductivity of the rebar) relative to the reference stimulus is measured by a lock-in amplifier and used to distinguish corroded and non-corroded rebars. The proof-of-concept sensor demonstration is able to resolve varying extents of rebar corrosion and can find potential applications as an NDT tool in a variety of industries.