Ground-penetrating radar
GPR works from one side of the slab, needs no evacuation of the area, and gives results on the spot. It locates rebar, post-tension tendons, conduit and voids, and the technician marks them directly on the surface.
X-ray (radiography)
X-ray produces a detailed image, but it needs access to both sides of the concrete, a radiation safety zone that usually means clearing the area, and more time to schedule and process.
Which one fits
- Elevated decks, slabs on grade, walls and tilt-wall panels for coring and anchoring: GPR in most cases.
- Very dense reinforcement or work where an image is required: X-ray may be specified.
- Occupied buildings and tight schedules: GPR, since nobody has to clear out.
Questions
Can GPR find post-tension cables?
Yes. Locating PT tendons before coring is one of the most common uses of GPR concrete scanning.
How deep can GPR see in a slab?
Typical scanning covers the full thickness of most building slabs and walls where tendons, rebar and conduit sit.