A PS200 Ferroscan cover meter was used. A 600mm square template was fixed to the structure and the area in question was scanned in two directions at right angles to each other, in a series of sweeps. A calibrated wheel on the search head records where the search head is at all times. Using electromagnetic principles and an on-board computer analysis, an image of the underlying reinforcement is shown on a screen. This is downloaded to a PC and analyzed in detail to give readout of bar sizes. The data is then saved to a Microsoft Excel file.
When conducting these tests, we made sure that the surface was uniform and level as possible since bumps and unevenness would cause variation from the correct readings.