Application Guide
GPR for Concrete Scanning & Structural NDT
Concrete-scanning GPR locates rebar, post-tension cables, conduits and voids before cutting or coring, and supports structural assessment of slabs, decks and walls.
Cutting a post-tension tendon or a live conduit is costly and dangerous. High-frequency GPR resolves closely spaced reinforcement and embedded services within the top few tens of centimetres of concrete, and can measure cover depth, slab thickness and the presence of voids or delamination.
Two technologies are used: conventional impulse GPR with a single high-frequency antenna, and stepped-frequency continuous-wave (SFCW) GPR, which sweeps a wide frequency band to combine shallow resolution with deeper penetration in a single scan.
Methods Compared
| Method | Detects | Typical Depth | Limitations |
|---|---|---|---|
| Impulse GPR (1.6–2.7 GHz class) | Rebar, conduits, PT cables, cover depth | Typically up to ~0.5 m in concrete | Single-frequency trade-off between resolution and depth |
| Stepped-frequency (SFCW) GPR | Rebar layers, PT cables, slab thickness, voids | Shallow to deeper elements in one scan | Higher cost; app/tablet-based workflow |
| Handheld concrete scanners | Pre-drilling and coring checks | Shallow | Spot checks rather than full imaging |
Depths are typical field values — actual performance depends on ground conditions, target size and survey design.
From spot checks to 3D imaging
Contractors drilling anchors need fast yes/no answers on the spot — compact handheld scanners do this well. Structural engineers assessing bridges, parking decks and tunnels need grid scans, 3D views and reports; full-size concrete GPR with tablet software is the better fit.
Recommended Instruments
A selection from our catalog. We source many more models — tell us what you need.
Which Condition Tier?
Concrete scanners are used daily and are often bought New or Absolute Certified. Refurbished handheld units are a common way to equip extra site teams at lower cost.
See the condition tier guide for what New, Refurbished, Absolute Certified and Surplus each include, or the industries overview for related sectors.
Frequently Asked Questions
Can GPR distinguish post-tension cables from rebar?
Usually, yes — PT tendons sit in a characteristic draped profile and different position from conventional reinforcement, and experienced operators identify them from the scan pattern before cutting.
What is SFCW GPR?
Stepped-frequency continuous-wave GPR sweeps across a wide frequency band instead of transmitting a single pulse frequency, combining the near-surface resolution of a high frequency with the depth of a lower one.
How deep can concrete GPR scan?
Typical high-frequency concrete GPR reaches roughly 0.3–0.6 m; depth depends on moisture, reinforcement density and the instrument.
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