Image-Reconstruction-Driven Magnetic-Resonance-Eddy-Current Test for Corrosion of Threaded Steel Bar in Concrete

To achieve the imaging and nondestructive quantification of threaded rebar corrosion in structures, commonly regarded as a highly challenging task, we introduce a three-coil magnetic-resonance-eddy-current testing (MRECT) technique. This electromagnetic inspection system operates by generating resonant magnetic fields that enhance the interaction with steel, mitigating the influence of the ribs on the rebar and enabling the detailed morphology evaluation for corrosion. In addition, we have developed a dedicated postprocessing algorithm to faithfully reconstruct the morphological profile of corroded regions. This algorithm effectively generates 2-D visualizations of corrosion patterns based on the MRECT scan imaging data. The system has demonstrated exact precision in measuring corrosion depth with a mean error of only 1.342 mm. In addition, it effectively quantifies the lateral extent of corrosion spread with an average error of 2.026 cm. This work provides effective technical support for addressing key challenges in the health monitoring of concrete structures, such as corrosion identification and structural safety assessment.