Nondestructive Evaluation of Localized Rebar Corrosion in Concrete Using Vibro-Radar Based on Pulse Doppler Imaging

Abstract

Early nondestructive inspection of rebar corrosion in reinforced concrete structures is important, but a practical, accurate, high-speed, and high-resolution method has not yet been proposed. We have proposed a vibro-Doppler radar (VDR) method for quantitative evaluation of rebar corrosion based on vibration displacement of a rebar sinusoidally vibrated by an excitation coil. However, this method is not practical because it is not quick enough, requiring two minutes for a measurement at one point. In this paper, a VDR system based on a pulse radar, which is 100 times faster than the conventional system, was developed, and its effectiveness was verified using a concrete specimen. As a result, it was found that a 30-cm section could be scanned in about 2 min. Furthermore, the vibration displacements spatially distributed on the rebar were monitored while the rebar was corroded by electrolytic corrosion tests. As a result, it was found that the vibration displacement increased locally with a width of a few centimeters, and their positions corresponded to the positions of sectional loss of rebar due to corrosion, indicating that this method can be used for nondestructive evaluation of localized rebar corrosion.

Multisensory Spatial Analysis and NDT Active Magnetic Method for Quick Area Testing of Reinforced Concrete Structures

“…However, only electromagnetic and mechanical-wave systems can assess reinforcement grids directly (and effectively). Mechanical-wave techniques can be utilized to test many different properties of RC [13,[22][23][24][25]. These techniques are well suited for testing concrete.…”

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

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Editorial for the Special Issue “Review of Application Areas of GPR”

“…Targeting the advantages that early detection of rebar corrosion could offer, the work by Miwa and Nakazawa [4] presents an overview of the use of vibro-Doppler GPR equipment to determine the spatially distributed vibration displacements associated with a rebar corrosion phenomenon. This contribution highlights how exploiting the Doppler-modulated component of a GPR reading enables new NDT applications with a high level of accuracy and efficiency.…”