Concrete Scanning Using GPR

locating rebar using ground penetrating radar

At Penhall Technologies, a division of Penhall Company, we specialize in concrete scanning using GPR (Ground Penetrating Radar). This technology detects common embedded objects and other subsurface hazards that are hidden in the concrete. Our service can be pivotal in your construction projects when it comes to cost reduction and damage prevention. Scan before you cut- avoid financial loss, safety hazards, and derailment of timelines.

At Penhall, we believe in a “zero incident” culture where safety is our #1 priority. For many years, contractors, engineers, and government agencies have come to trust Penhall first for safe and precise concrete scanning services. In addition to GPR concrete scanning services we offer private utility locating and x-ray imaging.

When You Scan First You:

  • Reduce your safety risk. Keep everyone on the job safe.
  • Reduce your financial exposure. (e.g. Accidentally Cutting a post tension cable can cost you thousands.)
  • Save time. Know exactly where to cut or drill to avoid a hazard and delays.

Scan Concrete and Detect Rebar with GPR – How it works:

GPR is a method that uses radar pulses to image the subsurface. This occurs when electromagnetic energy (in the form of radio waves) is pulsed into the substrate (ground, concrete, etc.) via an antenna at a certain frequency. These pulses reflect off of buried objects (such as pipes and conduits) and are then captured by a receiving antenna.

Detected items (such as rebar, conduit, post tension cable, pipes, among others) are revealed in real-time on the computer screen of the equipment as the GPR equipment moves along the surface. Collecting the data is relatively easy, the hard part is the analysis. Interpreting GPR requires a highly trained professional. Penhall is proud to have an extensive training program including over 300 OJT (On the Job Training) hours.

Locating conduit using ground penetrating radar

We only use equipment from the top GPR manufactures. Equipment that is state of the art, portable, and continually updated to meet the needs of our customers. By employing this equipment, it enables our analyst to access any proposed scan area and to move the equipment where needed. We have worked on high columns, areas surrounded by water, from vehicle mounted boom lifts, among other challenging scenarios. Our analyst are trained to analyze any proposed scanning area and choose the best method for your project.

Our equipment can scan concrete up to a 12 inch thickness, with 95% accuracy.  A greater scan depth can be achieved if the analyst has access to both sides of the concrete slab or surface (for example, a column). Once scanning is complete, our analysts mark the surface using different colors to differentiate the probable hazards within the concrete. In addition to field markings, Penhall offers various reports to fill the specific need of your project.

We use different equipment depending on your needs. Some of the equipment we use is listed below:

  • GSSI Mini
  • GSSI Utility cart
  • Hilti PS1000 X-Scan System

Concrete Scanning – Benefits and Limitations


  • GPR provides a real-time data that detects subsurface objects
  • GPR provides approx. depths of the objects
  • GPR can detect objects made of metal, plastic, and various other materials
  • GPR can also be used in utility locating, urban planning, structural verification, and construction pre-planning.


  • High-conductivity materials, such as clay soils and soils that are salt contaminated, reduce the depth of GPR ground penetration
  • “Green Concrete” or concrete younger than 3 months is unscannable due to moisture content
  • Considerable expertise is necessary to effectively design, conduct, and interpret GPR scans

What Is The Difference Between GPR And Digital Concrete X-Ray?

At times, these two services are believed to be identical. This creates uncertainty for the customer when choosing between the two. It’s important to understand some key differences between GPR and Digital Concrete X-ray before determining which to use on your next project.

Ground Penetrating RadarX-ray
Radiation ExposureNoYes
Interpretation of ScanSubjectiveDefinitive
Required Access to ScanOne side of a surfaceBoth sides of a surface
Scan TimeShort10 – 30 seconds per image
Occur during business hoursYesYes – requires some clearance parameters
Real Time InspectionYesNo
Large Area ScansContinuous no limitMultiple exposures
Standard Scan Size24 x 2416 x 16
Slab on GradeYesNo
Electromagnetic InterferenceYesNo

Determining the Cost of Your Concrete Scanning Project

Pricing for concrete scanning services is unique for each project. The ultimate cost is dependent on a number of factors such as:

  • Job location
  • Number and/or size of areas to be scanned
  • Depth of objects to be identified
  • Type of equipment needed to capture the image
  • Amount and/or complexity of the hazards believed to be in the concrete

Give us a call or email us for a more accurate price estimate.

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