Detection of Reinforcing Bars in Concrete by Electro-Magnetic Induction Method (Characteristics of Probe Coils)

Abstract

A Research has been executed to find the accuracy with which a dimension of reinforcement steel bars can be measured quantitatively by a electro-magnetic induction method. This paper describes the trial manufacture of various types of probe coils and the investigation of reinforcing steels in concrete with various changes of test frequencies.
As a result, it was found that the magnitude of signals was influenced by various probe coils, covering depth (the distance between probe coil and reinforcing steel), diameter of reinforcing steels and so on. In the case that the steel was of similar quality and the same diameter, the signal magnitude was influenced by the covering depth. When the covering depth was constant, it was obvious that the similar quality steels with different diameters had an effect on the phase angle and the signal magnitude.