Experimental study on detection of rebar corrosion in concrete based on metal magnetic memory

Abstract

This paper presents a non-destructive testing method for detection and analysis of rebar corrosion in concrete based on metal magnetic memory. A three-dimensional (3D) automatic scanning and measuring system, composed of a 3D scanning and measuring device and an automation software, was self-designed and developed. Two corroded reinforced concrete specimens were prepared by the accelerated galvanic corrosion test. A series of experiments were implemented by the proposed 3D device. The experimental processes involve acquiring the spatial position and corresponding 3D magnetic flux density near the specimens, judging the rebar's corroded region, and assessing the corrosion degree of the specimens. The results indicate that the curves of tangential magnetic field, obtained by the Y-scanning, all intersect near the edge of the steel corrosion zone, and the corrosion region can be qualitatively determined by the position and distance of the two intersecting points; the curves of tangential magnetic field, obtained by the Z-scanning, have an extreme value varying with the lift-off heights (LFHs) of the magnetic sensor in the corroded region, and the corrosion degree can be semi-quantitatively assessed by the LFH of the reversal point. The findings of this work propose an effective non-destructive detection method for rebar corrosion in concrete.