Ferroscan

Ferroscan is an electromagnetic pulse induction technology that detects steel reinforcement within concrete and measures the depth of concrete cover over it. TRSC uses Ferroscan as a complementary technology to GPR, while GPR provides broader subsurface imaging, Ferroscan provides more precise cover depth measurements and can estimate reinforcement bar diameter, making it the tool of choice when quantified cover data is the primary investigation objective.

Cover depth is a critical structural parameter. It determines the time for chloride penetration or carbonation to reach the reinforcement and initiate corrosion, the primary durability concern for reinforced concrete in Australian exposure environments. Accurate cover depth measurement is therefore essential for durability modelling, residual life assessment, and determining the urgency of protective intervention. At the Prince Consort Hotel, Ferroscan cover depth measurements across the heritage reinforced concrete elements provided the data needed to calibrate chloride diffusion models and estimate time-to-corrosion initiation.

Ferroscan technology works by generating a pulsed electromagnetic field that induces eddy currents in nearby ferromagnetic materials (steel reinforcement). The instrument measures the disturbance to the field caused by the reinforcement and, through calibration curves, determines the cover depth and estimates bar diameter. Measurements are taken on a scan grid and processed to produce a 2D reinforcement map showing bar positions, spacing, and cover depth across the scanned area.

The technology is particularly effective for cover depths up to approximately 80mm and bar diameters from 6mm to 36mm, the range relevant to most reinforced concrete construction. Beyond 80mm cover depth, signal strength reduces and accuracy diminishes. For deeper reinforcement or complex reinforcement arrangements (closely spaced or multiple layers), GPR is the preferred technology.