GPR vs. X-Ray for Concrete: Is One Better Than the Other?

If you’re looking to survey or otherwise examine an area that includes concrete, you probably already know that it’s difficult to check what lies beneath or within such a dense and hard surface layer. Unlike dirt or other malleable materials, concrete can’t be simply scooped out of the ground and returned with ease, nor can it be scanned efficiently with metal detectors. But concrete structure scanning is an essential part of construction, underground utility locating, and other industries, so the technology to do so does exist.

When it comes to scanning the concrete you are working on, you want to make sure you’re using the best equipment that yields the most detailed results. You are best off choosing either GPR scanning (ground-penetrating radar) or X-ray technology while scanning concrete. So when it comes to GPR vs. X-ray, which one will yield the results you’re looking for, and which one is the superior choice?

GPR Scanning Process

Ground-penetrating radar (GPR) scanning involves sending electromagnetic waves from a GPR receiver into a surface. When the electromagnetic waves bounce off a material within the concrete surface, a signal comes back to the receiver, creating a series of readings. When an experienced GPR technician interprets these readings, they can determine what material is below the surface.

Pros of Using GPR

Real-time readings

If time is of the essence on your job site, you might not have time to get offsite readings or results developed. GPR scanning provides technicians with real-time results, meaning you can get to work faster. However, faster isn’t better if you don’t also make sure the results are being read correctly. To best take advantage of speedy readings, you will need an experienced GPR technician who can read results accurately and confidently.

Only requires one slab side

One of the big factors to consider when choosing between GPR vs. X-ray is if you have access to both sides of the concrete slab you are scanning. In some cases, such as with vertical concrete supports, it is no problem to access both sides. If the slab is laid in the ground, it can be harder. X-ray scanning requires access to both sides of the slab, whereas GPR only needs access to one side of the slab. This makes it much easier to get results in areas with limited access.

Non-destructive

Because GPR only needs to scan one side of your concrete slab, there’s no need to dig anything out of the ground or disrupt your job site. This saves you significant time and money and keeps your job site open while other construction is taking place.

Cons of Using GPR

Readings can be subjective

Even the best GPR technicians can’t be absolutely certain what’s beneath the surface because GPR readings can be subjective. In many situations, drilling into or cutting open electrical conduits or other sensitive components by accident can be a costly mistake.

Electromagnetic interference

It can be a tougher choice deciding between GPR vs. X-ray scanning when you’re in an area with a lot of electromagnetic frequency. Since GPR scanning operates via electromagnetic signals, GPR can be affected by electromagnetic interference. In areas such as telephone service poles or near cable boxes, it may be difficult to get a precise result using GPR.

Conditions can scramble results

If your concrete slab is wet or has a lot of other materials inside of it, GPR results can come back scrambled. In areas where concrete is frequently getting wet, or places where concrete has been layered on top of older surfaces, GPR technicians might have trouble getting accurate results.

X-Ray Scanning Process

As you might have gathered from the name, concrete X-ray scanners are specialized X-ray machines. X-rays are created when negatively charged electrodes are heated up by electricity, producing energy. This energy is then directed towards a metal plate/anode at a very high velocity. When this energy collides with the atoms that make up the metal plate, an X-ray is created. 

Pros of Using X-Rays

Unparalleled accuracy

When you need to be absolutely sure of what’s underneath the surface of your concrete, X-rays are the way to go because they provide unparalleled accuracy. It doesn’t matter if a slab is wet, congested, or especially thick — with X-ray technology, technicians will be able to scan whatever is inside the concrete and view high-resolution images.

Results easier to read and comprehend

While it’s important to always schedule scanning with a professional service who can comprehend any and all results, when it comes to GPR vs. X-ray scanning, X-rays are simply easier to read. They can even be shown to property owners and managers as substantive proof that a layperson can grasp. GPR results tend to look more like graphs that are incomprehensible to those not trained in reading GPR results.

Scans show more detail than GPR

GPR is great to find what’s beneath concrete, but it can lack accuracy when something that should be beneath the concrete isn’t there. In other words, concrete X-ray scanning is much better at finding cracks, holes, or voids in concrete, which means X-ray might be the ideal choice in a situation where locating missing or damaged concrete is essential.

Cons of Using X-Rays

More expensive than GPR

Many people find X-ray scanning less cost-effective than GPR because it takes longer, requires more specialized equipment, and involves scanning both sides of a concrete slab. However, there are as many different individual situations as there are job sites, so it isn’t a guarantee that X-ray always costs more. 

Results often need to be developed

Concrete X-ray scanners can be film-based or digital. Film-based X-rays must be processed and printed offsite, whereas the newer digital X-ray technology allows for some onsite or real-time viewing. However, while digital advancements are promising, most X-ray concrete scanning is still film-based. This means the film needs to be developed and analyzed offsite, and you wait longer to continue your work at the job.

Requires extra caution and PPE

Because X-ray imaging involves radiation, extra personal protective equipment (PPE) is needed for everyone near the X-ray imaging location, as well as a 100+ foot zone of caution around the X-ray scanner. This means that you might need to temporarily shut down your job site while X-ray imaging occurs. A chief difference in GPR vs. X-ray scanning is this radiation danger. GPR is highly safe and only produces about 1/100th the radiation of the average cell phone, whereas continued exposure to X-rays can be dangerous over a period of time.

Your Next Steps

When you’re choosing between GPR vs. X-ray scanning for your job, it’s a matter of weighing the pros and cons. While it’s apparent that there are benefits and drawbacks to each scanning method, we’ll help you make the decision that is best for you based on your individual needs. Contact GPR One Call today with any questions or to get your project moving today!