Ruiqiang Zhao, Hong Zhang, Leng Liao, Jianting Zhou, Huixiang Ma, and Zhigang Li
Reinforcement stress, non-destructive testing, metal magnetic memory, 3D scanning device
This paper introduces a non-destructive testing technique for reinforcement stress in reinforced concrete (RC) structure based on the metal magnetic memory (MMM) effect. A self-designed three- dimensional (3D) magnetic field scanning and detecting device is proposed, and it consists of a high-resolution micro-magnetic sensor, a three-axial mechanical movement platform, and a computer-based automatic control system. The magnetic flux leaked from the RC under axial load, called as self-magnetic flux leakage, can be detected and assessed by employing the 3D magnetic field scanning and detecting device. Different features are found by analysing the self-magnetic flux leakage from specimens whose stress experienced different levels, especially different when the stress is in the elastic stage and in the harden stage. The distinction can be used to evaluate the stress state and then assess the health condition of the structure. The mechanism of the competition between the Earth magnetic field and the magnetic leakage field would be used to understand the different characteristics of self-magnetic flux leakage signals at different stress stages. The MMM technology can be used as a new method to conveniently detect and evaluate the steel stress of the RC structure.
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