Ground Penetrating Radar Scanner (GPR) is a directive energy scanning technique based on the analysis of the Electro-Magnetic Radar (EMR) signals that utilizes short duration high-frequency radio waves to “view” inside solid materials such as concrete, soil and rock. It emits a pulse of electromagnetic energy into the ground and listens for the echo from any buried object.
GPR typically looks like a wheeled cart or “lawnmower” and as you wheel it over the slab, the radar antenna sends pulses downward a small screen attached to the unit displays the reflections of the radar waves in real-time. This allows a skilled operator to analyze the data and identify concealed rebar, cables, voids and more.
Why Scan Concrete?
The concrete has a steel rebar that cables and pipes are running through it, it is common to find these elements inside walls and floors. Hitting one of these by chance with a saw can be hazardous and expensive. By scanning first, you will have a clear “roadmap” of what you’re dealing with. GPR is far quicker and safer than the old X-ray techniques – it can swiftly scan a slab from a single side and usually views 18–24 inches (45–60 cm) down in concrete.
In practice, a scan will detect:
- Rebar and post-tension cables
- Electrical/plumbing conduits
- Voids or cavities
These reflections show up as unique patterns on the GPR screen enabling you to identify safe drilling areas. In fact, a lot of pros recommend scanning all concrete prior to coring, drilling or cutting more than a few inches.
Which GPR Scanner Is Right For You
Frequency and Penetration: Antennas of higher frequency (GHz) provide more detail but only penetrate to shallow depth, while lower frequency penetrate to greater depth. Choose a frequency depending on the thickness of your slab and on the size of the object.
Portability: Many concrete GPRs are handheld or run on carts. A small, ergonomic (such as the PS1000 by Hilti) is easier to push and less tiring. If you are scanning ceilings or walls, lighter wands or antennas then paddles come in handy.
User Interface: Choose a software that is user friendly and has a good real-time display. Some scanners produce immediate 2D/3D images and allow exporting of data for reporting purposes. And if you just want things to be simple, you can use a basic handset, if you have a complex job, there are software and mapping options that are worth it.
Cost and Training: Handheld GPRs cost in the range of $10–15K, with high-end models going above $30K.
Consider the support: Many manufacturers provide operator training or certification to help you utilize the device properly and safely.
Recommended Ground Penetrating Radar Scanner
Leica C-thrue (formerly known as IDS) is a dual-antenna handheld scanner for easy handling, capable of detecting rebar, cables and voids up to a depth of approximately 31 inches. Best value for today The Hilti PS 1000 X-Scan is a compact and convenient paddle-type scanner with real-time screen display to help orient users to rebar and conduit spacing up to 12” depth, great for slab scanning on the go.
The Proceq GP8000 series provides compact and lightweight ground penetrating radar (GPR) systems that are designed to the point of use with modern mobile devices, offering an intuitive interface and rugged design that make these units truly unique, although the depth is limited compared to larger systems. GSSI StructureScan Mini and Flex NX: If you are aiming for professional-grade imaging, GSSI’s StructureScan Mini and Flex NX systems are the way to go, the Flex NX allows you to use both 1.5 GHz and 2.5 GHz antenna(s) to optimize between depth and resolution, providing the most detailed 3D imaging at a higher price point.
Each tool has its compromises. For home users or small busy contractors, simpler units (like Proceq and Leica) are a godsend. If you scan frequently or need to scan deep, a higher powered system (such as GSSI’s) may be worth the outlay.
Safety and Regulations
Ground Penetrating Radar Scanner (GPR) is a reliable and non-destructive method that emits low-energy radio waves and does not generate ionizing radiation, which accounts for its safety for human use and ability to protect the concrete structure. Gut-wiring or busting out walls to do x-ray scans GPR is much safer and leaves your concrete in place.
That being said and just as with any process on a construction site, you should take usual safety precautions while conducting GPR scans, which may allow or require you to wear hard hats, eye protection and high-visibility clothing and you should assess any potential hazards (traffic, power lines, etc.) and use your established safe operating procedures.
The equipment must meet wireless rules, e.g. FCC in the US or CE in Europe, and in many countries operators must be trained or certified. Suppliers and trade bodies, including CSDA, provide training to support correct interpretation and appropriate parameters of use for GPR. Ground Penetrating Radar Scanner is best used on smooth dry surface like concrete or earth, although rain or moist soil can degrade the signal.
It also cannot penetrate solid metal objects, such as thick rebar mats or steel plates, which may necessitate using a different method or a backup scan in another location to confirm your findings.
Conclusion
Ground Penetrating Radar Scanner might sound like high-tech science fiction, but it’s really a practical tool. Even entry-level units are pretty simple: once you know the basics, you just roll the device over the slab and the buried objects appear in real-time. “It’s like giving yourself ‘X-ray vision’ for concrete, which helps prevent errors and injuries.” GPR units are high quality, rugged and easy to use, with minimal training or even no training at all an operator can begin using one immediately.
We at PrimeTestEng rely on cutting-edge GPR technology that is dependable, user-friendly, and robust. Operators can begin scanning immediately for safe, accurate, and effective results with little to no training.
Keep in mind: for the price of a GPR scan (which is usually only a couple thousand dollars), you could save yourself from an expensive mistake, potentially saving you time and money on repairs down the road.
