A concrete cover meter is a specialized instrument designed to locate rebar and measure concrete cover. Rebar detectors are different, less sophisticated instruments that only locate metallic objects below the surface. The concrete cover meter is commonly used with pulse induction rebar-detection methods.
Cover meters work based on the principle that steel within concrete and masonry will be affective by the magnetic field applied by the device. When a magnetic field is forced through a magnetic material, it opposes the change in a certain amount of eddy current and then produces its magnetic field in the opposite direction of the applied field. The strength of the eddy current and the opposing magnetic field depends on the magnetic properties of a material that was subject to the applied field and the distance between the two.
By setting a specific magnetic property for the reinforcing bars with the use of a standard bar size, the device can then predict the location and depth of the reinforcing bar. This is possible as the cover meter pulses the magnetic field and measures the opposing force created by the eddy currents within the ferrous material inside the masonry, which is most likely coming from the reinforcing bars. With this principle at work, the cover meter can accurately and efficiently calculate the distance to and between reinforcing bars and even locate the precise bar position.
Some advantages of the pulse induction method using cover meters include its high accuracy, low cost, and precision as it is not affected by environmental influences nor is it affected by the heterogeneities and moisture of the concrete being tested. Like any other testing methods, however, the cover meter also has its limitations and disadvantages, such as restricted detection range and dependency on cover depths when it comes to minimum bar spacing detection.
Papworths Construction Testing Equipment (PCTE) 