The inductive scanning system is a non-destructive testing technique that utilizes the phenomenon of eddy
current induction and detection for imaging steel reinforcing bars embedded within concrete. In this paper the
inductive scanning system using a heterodyning sensor in combination with real time digital signal processing
(DSP) has been used to detect and generate images of corroded reinforced steel bars embedded within the
concrete. The sensor generates a vector of voltage values of the reinforced bars scanned at a spatial interval.
These voltage values are processed by the DSP to produce voltage signals and generate images. The feasibility
of exploiting the inductive scanning system to detect and distinguish different amounts of corrosion on steel
bars embedded in concrete was investigated by using one-dimensional scanning techniques, such as parallel
line scans and orthogonal line scans for single and multiple corroded steel bars. In these techniques, signal
profiles of various amounts of corrosion on steel bars were compared and analysed. The system shows
evidence of very good performance which encourages its development and use in corrosion detection and
monitoring.
Keywords: Heterodyne sensor, image, signal profile, corrosion, non-destructive testing, inductive scanning