GPR SCANNING
Our GPR services can detect a variety of subsurface features.
Identifying the type and location of subsurface features is a necessary step prior to cutting, coring, and breaking. There are a number of common subsurface features located within concrete. We analyze the data generated using GPR to determine the location and types of features present below the surface, giving you the ability to efficiently drill, saw, or break while preserving the integrity of the structure and reducing the need for patching or other costly repairs.
Rebar detection
Steel rebar is integral to the structural integrity of any concrete slab. Individual slabs of concrete can house hundreds of feet of rebar. With GPR, we can locate subsurface rebar and rebar patterns and precisely mark their locations, making it safe for you to cut, core, or break the concrete.
Post-tension cable detection
Post-tension cables are under extremely high tension. If post-tension cables are cut, they can break the concrete structure and pose an imminent threat to the safety of on-site crew. We can use GPR to locate post-tension cables, mitigating safety hazards and maintaining the integrity of the concrete.
Pipes and conduits detection
Electrical wires encased in conduits are often run through concrete slabs, and pose a shock risk. Not only are they safety hazards, cutting electrical wires can cause a power outage. This is a major inconvenience in terms of time and money. Using GPR, our expert crew can detect the location of pipes and conduits, preventing mistakes when it is time to cut, core, or break concrete.
Voids and deterioration detection
Voids in concrete—air gaps between the subgrade, dirt and the concrete slab-on-grade—occur over time due to erosion, compaction, and pipe ruptures. Voids and general deterioration affect the overall structural integrity of concrete slabs, but such imperfections are undetectable without specialized scanning equipment. We can use GPR to scan for voids and clearly mark their locations, ensuring that construction continues without the threat of collapse.
CALL THE PENHALL TECHNOLOGIES HOTLINE TO GET A TECHNICTIAN OUT TO YOUR PROJECT TODAY!
DIGITAL X-RAY IMAGING
Digital X-ray produces a clear, definitive image of the subsurface, whereas ground penetrating radar (GPR) uses radio waves to produce a radargram, which shows subsurface undulations.
There are two ways in which to locate subsurface features within concrete: X-ray imaging or GPR. There are advantages and limitations to each process. At Penhall, we provide both services—we can work with you to determine the concrete scanning type most suitable for your project.
Digital X-ray imaging:
X-ray can be used in situations in which GPR is not effective, or when clear, definitive imaging is required. Highly congested slabs are ideally suited for the application of digital X-ray. Scanning concrete with X-ray can be performed on concrete of various thicknesses. Penhall’s digital X-ray technology acquires images immediately, allowing the radiographer to examine and mark the location and exact type of subsurface feature without the need to develop film at a lab.
Digital X-ray does require access to both sides of the concrete slab and is not suitable for scanning slab-on-grade concrete. Also, unlike GPR, digital X-ray cannot be used to determine the depth of subsurface features, only the location, size, and type.
GPR scanning:
Ground penetrating radar is also used to detect subsurface features, including rebar and rebar patterns, post-tension cables, and pipes and conduits. GPR can detect voids and deterioration within concrete, making the process ideal for avoiding potential structure collapse. GPR emits radio waves that travel through concrete and map the various undulations in the waves’ paths. This produces a radargram, which is interpreted to determine location, depth, and type of feature within the concrete. It does not require access to both sides of the concrete and can be used to scan slab-on-grade.
GPR cannot produce a clear, definitive image of the subsurface like digital X-ray imaging. The data GPR produces must be interpreted once scanning is complete in order to identify the types of features present in the slab.
| Feature | GPR | X-Ray |
|---|---|---|
| Radiation Exposure | NO | YES |
| Access to both sides? | NO | YES |
| Power required? | NO | YES |
| Restricted Area? | NO | YES |
| Resulting Image? | NO IMAGE | CLEAR IMAGE |
| Interpretation? | SUBJECTIVE | DEFINITIVE |
| Determine Size? | NO | YES |
| Determine Depth? | YES | NO |
Digital X-ray imaging vs GPR:
Digital X-ray and GPR both locate features within concrete. However, they accomplish this result differently.
X-ray can definitively identify the location and type of feature embedded in concrete because it produces a clear image. Because Penhall uses digital processing, the scanning process is safe and efficient. Digital X-ray is more specialized as it cannot be used to scan slab-on-grade concrete.
GPR does not produce images, but rather data that can be interpreted by a trained analyst, who will use the information to identify the location and type of feature within the concrete. GPR can be used to scan slab-on-grade and other concrete that is only accessible from one side.
UTILITY LOCATING
Our utility location experts can detect and mark subsurface hazards which would otherwise endanger your project and personnel.
Penhall Technologies provides private underground utility locating services for construction and demolition projects of all types and scales, all across the country. Using ground penetrating radar (GPR) and X-ray imaging technology, our experienced team members can detect, identify and label underground utility lines, tanks, and pipes.
This ensures that you can take the precautions necessary to avoid striking subsurface hazards during construction or excavation, keeping your team safe and your project on track.
Please note that we locate utilities on private property, while 811 locates public utilities from the street to the meter. After locating your utilities, our analysts mark each line with paint or flags in their designated color in accordance with the APWA.
CALL THE PENHALL TECHNOLOGIES HOTLINE TO GET A TECHNICTIAN OUT TO YOUR PROJECT TODAY!
GPS Utility Mapping
We can generate a detailed map of your site’s utilities for future reference.
Relying solely on traditional utility locating is ideal for sites that you know won’t be disturbed in the future. However, if future work may be necessary, GPS utility mapping provides you with a convenient, permanent reference that eliminates the cost of repeating the utility locating process.
Our GPS utility mapping service takes the location data generated from our utility location process and uses it to create a detailed map of a site’s underground utilities that can be exported as a KMZ or KML file for use with Google Earth, or a shapefile (SHP) which can be viewed in ArcGIS. All utilities are color coded, and can be tagged with latitude, longitude, date, and any other metadata you need for the job. Photos can also be incorporated into the map file as well.
GPS utility mapping does away with the need for having to pay for GPR or electromagnetic utility locating every time you need to dig. Instead, you can refer back to your personalized utility map and use a GPS unit to relocate utilities, allowing you to dig with confidence. GPS mapping is accurate to within 6 inches—far more accurate than needed for the tolerances of most underground work.