Ground Penetrating Radar technology can effectively be applied to locate and distinguish a multitude of metallic and non-metallic materials. Ground Radar is most effective in instances where there is a large difference between the electromagnetic properties of the materials being surveyed. Because of this, metallic objects make ideal targets (e.g. reinforcement within concrete). Ground radar will however detect most materials providing there exists a sufficient difference within the electromagnetic properties between the target and surrounding material. A number of the more common target materials include:
- changes in ground strata and geological features
- air pockets or voids
Excavated areas, back-filled areas and other types of ground disturbances can also be identified and mapped.
Ground Penetrating Radar will not work in certain ground conditions such as heavy clay soils, especially if they are saturated with water. De-ionised water won’t pose an issue with Ground Penetrating Radar; however water that has a high mineral content (e.g. sea water which has large amounts of salt) absorbs a big part of the signal causing it to be an unsuitable medium. Additionally, Ground Penetrating Radar is not able to see “behind” metallic objects, including dense reinforcement.
It must be remembered that Ground Penetrating Radar is a relative method. It detects changing conditions coming down from the surface but will not ascertain the absolute nature of many materials surveyed. It is often important to supplement the Ground Penetrating Radar data with absolute data obtained from boreholes, sample cores, trial pits, potholes, etc.