Cover Meter Testing

We use cover meter testing in conjunction with our other concrete testing methods; the benefit of the cover meter is that it is a completely non-destructive test a very reliable first indicator.

Cover meter testing will locate rebars and measure the exact concrete cover over the re-inforced steel bar.

Cover meters are electromagnetic in operation. Electric currents in a coil winding in the search head generate a magnetic field which propagates through the concrete and will interact with any buried metal present, such as reinforcing steel.

The interaction will be due to either or both of two physical properties of the steel:

  1. it’s magnetic permeability
  2. it’s electrical conductivity

For a full description of technical explanation of cover meter testing, see Wikipedia

Adequate cover to the steel reinforcement in a concrete structure is important to ensure that the steel is kept sufficiently protected in the concrete to be well away from the effects of carbonation or other chemical reaction.

However, excessively protected cover has its own problems; crack widths may be increased and the lever-arm decreased.

In practice, by assuming that only one bar is present within the primary magnetic field, the cover meter can be calibrated to convert signal strength to distance and hence to indicate the depth of cover.

If there is more than one bar (or even scaffolding!) within the range of the primary field the instrument will receive a greater signal and indicate a shallower cover than the true cover. The skilled operator will always carefully map out the position and orientation of the steel, breaking out some steel if necessary, to ensure that accurate results are obtained.

Care must always be taken when dealing with multiple bars and the effects of adjacent steel such as window frames or scaffolding as mentioned earlier.

The latest cover meters now provide an image of the reinforcement under the concrete surface.

Call us on 0800 433 4788 or email
to discuss cover meter testing or any other concrete tests