Quantitative Detection of Corrosion State of Concrete Internal Reinforcement Based on Metal Magnetic Memory

Abstract

Corrosion can be very harmful to the service life and several properties of reinforced concrete structures. The metal magnetic memory (MMM) method, as a newly developed spontaneous magnetic flux leakage (SMFL) non-destructive testing (NDT) technique, is considered a potentially viable method for detecting corrosion damage in reinforced concrete members. To this end, in this paper, the indoor electrochemical method was employed to accelerate the corrosion of outsourced concrete specimens with different steel bar diameters, and the normal components B z and its gradient of the SMFL fields on the specimen surfaces were investigated based on the metal magnetic memory (MMM) method. The experimental results showed that the SMFL experimental B z curves are consistent with the analytical results of the theoretical model. Furthermore, the crest-to-trough behavior on the B z signal curve and its zero-point gradient spacing can more accurately indicate the corroded area's extent. Then, a magnetic characteristic parameter W based on a large amount of experimental data was established to characterize the degree of corrosion of the steel bars. The magnetic characteristic parameter W is linearly related to the maximum cross-sectional area loss rate of the corroded reinforcement. This paper will lay the foundation for future research on corrosion detection of reinforced concrete structures based on the MMM method and provide a feasible way for non-destructive detection of corrosion independent of the influence of reinforcement diameter and magnetization history.