Concrete Scanning Blog

Four Reasons Why Concrete Scanning Is Essential For Your Project

concrete scanning

Concrete scanning is a method that finds subsurface hazards through the use of GPR (Ground Penetrating Radar). Some of the objects that GPR detects during scanning include: pipes, conduits, post tension cables, utilities, live wires, rebar, and voids, among others. But, why is it important to find and identify these objects?


When cutting into concrete without scanning first, there is a possibility that you will encounter a subsurface object or hazard. In some incidents, hitting an object can injure the workers at the jobsite. For example, cutting into a post tension cable. The released tension after the cut can cause the cable to snap or expand, causing a blowout. In addition, your workers could be electrocuted by striking a live conduit.


Striking any subsurface objects can result in delays for your project. Quite often, clients call us after they have hit an object in the concrete. Unfortunately, they have learned the hard way. Now they have decided to scan the rest of their project to ensure that it doesn’t happen again. Other times, the repairs needed to fix the damage that has occurred can cause delays. Avoiding these incidents will help to ensure that you can complete your project on time.

concrete scanning markings


Without hiring scanning services before, one may assume concrete scanning is simply an additional cost to a project. In reality, scanning offers a significant cost savings! By having a clear picture of a proposed cut, core, or trench area, you are no longer playing a guessing game. This provides a tremendous financial benefit by preventing repairs and additional services that result from striking a subsurface object. As mentioned before, concrete scanning helps your projects stay on time. Whereas a project that encounters delays can cost more money.


One of the most significant benefits of concrete scanning is accuracy. You can proceed with your project knowing that the proposed layout areas for any drilling, coring, or cutting are safe. On many projects, our analysts find hazards in the layout proposed by the client. If the client hadn’t decided to scan, there is a possibility they would have encountered many of the problems mentioned.

For these four reasons, concrete scanning is a vital method for your project. At Penhall Technologies, we value your time and safety, so we make sure that our services convey that to your project.

September 1, 2017

What to Expect – Concrete Scanning for Your Construction Project

concrete scanning

Deciding to scan concrete for your project was a smart decision for many reasons. It saves you time by knowing where to exactly cut, drill, or core. It saves money by preventing damages. And, most importantly, it keeps your project safe. Now that you want to move forward with our scanning services, here is what you should expect.

One of our expertly trained GPR analysts will arrive at the jobsite. Before they start scanning, they will meet with you to discuss the areas that you want scanned. You would need to provide a layout for the analyst to scan.

After this, the analyst is ready to scan. GPR (Ground Penetrating Radar) is safe to use during regular business hours. This means that any trades on the jobsite can continue with their job while the scanning takes place.

The analyst might use different types of equipment depending on the job itself. Our analysts carry the GSSI Mini XT. This equipment is ideal for locating rebar, conduits, post-tension cables, voids, and real time determination of concrete slab thickness. They also use the GSSI 2000 MHz palm antenna. This equipment works in small spaces, approximately 2” from the wall. In addition to the GPR equipment used, all analysts are also equipped with an RD 7100 unit. This unit is ideal for locating live conduits within walls, slabs, or ceilings.

concrete scanning marks

While the scan takes place, the data shows up in real time. Our analysts can interpret the data and from there he/she can mark any objects directly on the concrete surface with tape, chalk, keel, or markers (as pictured above). Then, the analyst would communicate their findings with you.

Sometimes, the proposed layouts are clear and ready for coring or drilling. Some other times, the analyst finds post tension cable, rebar, or other objects in the area where the coring or drilling is proposed. If this is the case for your project, you can propose a second layout location. The analyst will then proceed to scan that area to make sure that it is clear and safe.

After the scanning, a summarized written field report of the findings will be provided you. With this piece of information, in addition to your field markings, you can make decisions as to where to cut, core, or drill. Additional electronic reports are also available upon request, including pictures and 3D scans. These reports take additional time and will be completed off-site and will be emailed to you.

Now you know what to expect when hiring Penhall Technologies for our concrete scanning services. When our analysts arrive on site, you will find that you have gained a trusted partner who will undoubtedly add value to your project. Regardless of the project scale, our analysts always come prepared and ready.

August 25, 2017

GPR or X-Ray – How to Determine What Your Project Needs

GPR - ground penetrating radar service

GPR analyst on a concrete scanning job


Now that you have decided to scan first, you might be wondering what suits your project’s needs: Ground Penetrating Radar (GPR) or digital X-Ray? Penhall Technologies offers GPR services nationwide, and X-Ray services in Seattle, San Diego, and Los Angeles. Both concrete scanning methods help you locate subsurface objects and hazards. However, they are both unique, and have different uses.

More often than not, GPR would be the first step to locate any subsurface objects in concrete. GPR analysts start by marking the desired area, which the customer provides a layout of. Then, the analyst proceeds to scan with a handheld device (see picture above). Based on the collected and analyzed data, the analyst would mark the objects found with chalk, keel, or tape. This process goes smoothly under ideal concrete circumstances.

There are a few factors to consider when seeking GPR or digital X-ray services. First, what concrete structure or structural components are being scanned. Digital x-ray is not an adequate option for your project when you are looking to identify objects or hazards in a slab on grade. Digital X-ray requires both sides of the location in question, such as a slab, column, or beam.

The second factor to consider is the location of the project.  If patrons, occupants, or employees are present at the jobsite, GPR scanning can be done during regular business hours. People don’t need to vacate the area. This is ideal for projects and renovations in sites such as hospitals or hotels, where people may be regularly coming and going.


Penhall's GPR analysts

Penhall Technologies’ analysts demonstrating digital x-ray


Sometimes, after completing GPR concrete scanning, the results may show a highly congested area. This means that the analyst collected data that may be extremely difficult to interpret. This leads to inconclusive labels for field markings. This is when digital X-Ray comes in.

Digital X-ray shows a clearer depiction when it comes to imaging the interior contents of an area that’s congested. For this reason, this method is preferred under these circumstances.

Digital X-Ray is not always a service that follows GPR concrete scanning. We recommend pursing digital x-ray as an option when the jobsite in question is highly congested with structural components such as rebar, wire mesh, and tension cables. Or when you simply want a clear precise image of the area.

Both GPR and X-ray can provide valuable information prior to cutting, sawing, or drilling. It will also keep your project on time, on budget, and most importantly- safe! For more information regarding GPR and digital x-ray scanning services, give us a call at 844-211-5300.


August 4, 2017

Concrete Scanning Using Ground Penetrating Radar (GPR) – Common Misconceptions

Penhall analyst conducting concrete scanning

Concrete Scanning Using Ground Penetrating Radar (GPR) – Common Misconceptions

Ground Penetrating Radar (GPR) is a very effective scanning method to ensure safety when coring or cutting into concrete. However, there are still a lot of misconceptions about what GPR can and cannot do. This list will help you understand GPR before you hire a concrete scanning service for your project.

I can scan myself if I buy the equipment

While setting up and using the GPR equipment is easy, interpreting the data is complicated. A major misconception is that GPR shows a clear image of what is in the concrete. Actually, the screen reflects a black and white image resembling TV static. When the antenna picks up on an object, it reflects as a hyperbola on the screen. GPR analysts go through extensive training to be able to interpret the data, and to know how to differentiate between objects on the screen.

GPR can be successful under any surface condition

Moisture in concrete plays a huge role in the success of concrete scanning. Moisture raises conductivity, meaning the equipment’s signal bounces right back, making it difficult to get good data readings. Concrete that is less than three months old has a higher moisture content than concrete that has had more time to cure so it’s best to wait before scanning. Other difficult surfaces can include insulation, marble, granite floors, among others.

underground wire locating

Analyst performing underground wire locating

GPR can scan at any depth

The GPR equipment in concrete scanning applications is only able to scan up to 20 inches. If we have access to both sides of the slab, then the analyst would be able to scan thicker concrete.

The GPR equipment can differentiate between objects

As mentioned before, the screen of the equipment shows data in a very general state. Different objects, such as post tension cable or rebar, aren’t displayed in a distinctive way, nor do they show a difference in the hyperbola. Thanks to the expertise of the analyst, he/she can distinguish between the different lines and patterns to read the data.

GPR is 100% precise

While GPR is considered to be one of the most effective forms of non-destructive testing, it is not perfect. GPR is as accurate as one-fourth of an inch from the center of the target and less than half-inch in depth under ideal circumstances (for example, well-aged concrete). Some of the variables in the concrete that affect accuracy can be: wire mesh, pan decking, and multiple layers of rebar.

We hope that this list gave you a better understanding of GPR concrete scanning. By deciding to scan the concrete at your jobsite, you are reducing safety and financial costs for your construction project. To learn more about Penhall Technologies’ GPR concrete scanning and utility locating services, read our previous blog posts here.



August 1, 2017

Case Study: How Concrete Scanning Can Assist with Locating Structural Reinforcing

Case Study: How Concrete Scanning Can assist with Locating Structural Reinforcing

At Penhall, safety is our #1 priority. So, when we were called by a general contractor to help out with an investigation of a potentially hazardous construction project, we were honored to help. The investigation was brought on by safety issues in the construction of a high rise hotel in the booming city of Austin, TX.

Penhall assisted with locating structural reinforcement in 49 poured-in-place columns on the first floor of the building, which was proposed to go up to 30 stories.  The goal of this project was to locate the placement of the vertical pieces of rebar along with the horizontal bands. If columns are not properly poured and installed, it can be detrimental to the integrity of the building as a whole.

gpr identifies improper rebar spacing in concrete columns


Austin GPR Analysts worked diligently to scan and mark the columns to verify the reinforcements.  The results, as you can see in the image sequence above, were very telling.  48 of the 49 columns had improper spacing of the rebar, meaning they lacked the structural integrity to withstand the weight of a multilevel building.

Following the analysts’ findings, the general contractors made the decision to fix all 48 columns. This allowed the project to resume, and allowed it to be completed safely.  Penhall walked away from this project with peace of mind knowing that our work minimized the threat of a potentially hazardous situation.

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June 30, 2017

We Scan For

  • Pipes and Conduits
  • Post-Tension Cables
  • Utilities and Live Wires
  • Rebar and rebar patterns
  • Voids within the Concrete
  • Structural Integrity of the Concrete