Ground Penetrating Radar
What is GPR used for?
- Post-tension cables
- Plastic and fiber optic conduits
- Detect voids, delaminations, and cracking 1/4-inch or greater within concrete.
- Detect voids under concrete slabs
- Measure concrete slab and deck thickness to within +/- 1/4-inch
Example: Roof level of the cast-in-place concrete structure. Above is the side view of the top and bottom layers of reinforcement in the 2’ X 2’ area.
- Ability to penetrate across concrete-air interfaces
- GPR is safe for employees and electronic equipment in work zone. X-ray is extremely dangerous.
- GPR will scan large areas faster than other methods. X-ray is extremely slow.
- GPR needs access to only one side of concrete surface to scan. X-ray requires two sides.
- GPR images are archived in 2D and 3D format and can be easily transmitted electronically. X-ray is 2D only.
- GPR is very accurate, typically locating objects to within ± 1/4”. X-ray does not provide a distance from surface to object measurement.
- Congested concentration of reinforcement at top of slab can prevent penetration of radar signal beyond top reinforcement to locate any lower objects in the slab.
- There needs to be contrast between the item to be located vs. material scanned.
- Need for experienced operators required to operate equipment and interpret results