Magnetic Data Pattern Features at Longitudinal Defect Sites in Rebars Scanned by a Passive Magnetic Inspection Technology

Abstract

Reinforced concrete is a versatile modern construction material. Despite its advantages as a composite material, corrosion of the embedded reinforcing steel leads to infrastructure deterioration and loss of service. Non-Destructive Testing (NDT) methods are required to quantify the reinforcement condition, and to help manage human and financial risks arising from unexpected outright failure or service restrictions. Reinforcement condition can be assessed using a novel, time- and cost-efficient NDT method based on the self-magnetic behaviour of ferromagnetic materials. In this study, the magnetic properties of three similar rebars, each having three similar sized longitudinal defects, are recorded and assessed through experiments and a numerical simulation model. Strong correspondence is demonstrated between the magnetic properties from numerical simulation and from the experimental objects. For instance, applying the experimentally obtained defect detection threshold to the mathematically simulated results allows accurate defect detection in the simulations, showing that self-magnetic behavior is a powerful tool for condition assessment of ferromagnetic reinforcing materials.

Evaluation of Reinforced Concrete Structures with Magnetic Method and ACO (Amplitude-Correlation-Offset) Decomposition

“…One of the RMTs is the Magnetic Memory Method (MMM). The method can detect abnormal conditions arising from changes in crystalline structures of rebar material resulting from stress concentration, corrosion, or cracks [ 3 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ]. The magneto-resistance (MR) and Hall effect sensors are most commonly used in the magnetic test.…”