Cover-meter

Applications
  • Depth of cover and diameter of reinforcement bars close to the surface of concrete, and bar location.
Method

Cover-meter is a good complementary technique to GPR scanning as it can provide an estimate of bar diameter and more accurate depths of cover. Cover meter results are utilised in conjunction the with GPR to supply steel detail for structures.

Cover-meter in Use to locate Reinforcement Bars
Data analysis and presentation

Depth of cover and bar diameter measurements are usually provided on CAD drawings along with the results of GPR scanning and any other techniques that are employed.

Example of presentation of NDT results: GPR, Schmidt Hammer, Impact Echo, Cover meter, core results.

Limitations include:

  • The cover-meter can only provide accurate depths of covers to a depth of approximately 80 mm (provided the bar size is known). Bars can be detected to depths of approximately 120 mm.
  • The cover-meter can only determine bar diameters at depths less than 60 mm provided there is sufficient distance (typically 200 mm) from neighbouring bars. The cover meters bar size measurements are typically only accurate to within +/- 20%.
  • Welded mesh will also produce over estimates of diameters and lower estimates of depth of covers. Cover-meter cannot determine whether the reinforcement is welded.
  • Any lapped bars or extraneous metal close to the measuring point will result in inaccurate results.
  • Cover-meter accuracy decreases with depth and decreases with closer reinforcement spacing.
  • Cover-meter cannot discriminate between closely spaced bars. Typically resolution is equal to the depth of cover.

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