GPRS’ precision concrete scanning services helped ensure the safe coring of concrete slabs during renovations to the fifth-oldest veterinary college in the United States.
Project Manager Bradley Oberklaus provided safe coring locations within buildings that are part of Washington State University’s 125-year-old College of Veterinary Medicine.
According to its website, the college has seven main facilities totaling more than 1.5 million square feet on the WSU Pullman campus and throughout the university system. The college features state-of-the-art laboratories equipped with the latest technology to train students in neuroscience and the molecular biosciences, as well as those earning their Doctor of Veterinary Medicine and other graduate degrees.
The college also houses one of the state’s only biosafety level 3 laboratories, which is designed to study infectious agents or toxins that may be transmitted through the air and cause potentially lethal infections.
The contractor needed to core through the beam-and-joist slabs as part of plumbing work related to the renovations. There was no existing documentation indicating where structural components or utilities may be embedded within the slabs, and striking one of those obstructions would have derailed the project and potentially even endangered the workers completing the concrete coring.
Also known as ribbed slabs or joist slabs, beam-and-joist slabs feature a series of parallel ridges that run along the length of the slab. These ridges are created by constructing a system of ribs or beams underneath the slab, usually made from precast concrete or steel. The ribs are spaced apart at regular intervals and extend from one edge of the slab to the other, providing additional support and strength.
GPRS utilizes ground penetrating radar (GPR) scanners to locate rebar, post tension cables, electrical conduits, voids, and more within all kinds of concrete slabs. GPR scanners emit radio waves into concrete slabs and detect the interactions between these waves and any subsurface objects to create a readout of hyperbolas that vary in size and shape depending on the type of material detected. GPRS’ SIM-certified Project Managers (PMs) interpret this data to tell you what was located and estimate its depth within the slab.
Our PMs can also provide GPR scanning services to determine key slab information for structural engineers, including concrete cover and overlay thickness, concrete thickness, and even dowel placement. We aren’t limited by the size or scope of your site; we have the training and the equipment to fully evaluate your concrete structure.
GPRS’ commitment to Subsurface Investigation Methodology (SIM) has allowed us to achieve and maintain a 99.8%+ accuracy rate when conducting concrete scans.
SIM is the industry-leading training program and process for not only concrete scanning, but also utility locating and sewer pipe inspections. It addresses a step-by-step approach to collecting subsurface data to ensure that the results are repeatable and accurate. SIM practitioners must follow a checklist designed to guarantee optimal results during every concrete scan and utility locate they complete.
Because GPRS adheres to SIM, we’re able to offer our proprietary Green Box Guarantee. Simply put, when we place a Green Box within a layout prior to anchoring or coring concrete, we guarantee that the area will be free of obstructions.
If we’re wrong, we agree to pay the material cost of any damage that occurs.
At Washington State, Oberklaus scanned the beam-and-joist slabs and provided several Green Boxes where the contractor could safely core for the plumbing work.
“It’s an amazing feeling to leave a job site where the customers are happy and confident in doing their work once I’m gone,” Oberklaus said. “It means the world to know that we’re trusted with the safety of so many people, every day.”
From skyscrapers to sewer lines, GPRS Intelligently Visualizes The Built World® to keep your projects on time, on budget, or safe.
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Frequently Asked Questions
How is GPR used to identify tendons vs. rebar in a post-tensioned slab?
In post-tensioned structures, we typically find one mat of support rebar near the base of the slab. This mat is generally consistently spaced and remains at a constant elevation. Post-tension cables are generally found above this support mat and “draped” throughout the rest of the structure. The elevation of the cable is usually high near the beams and column lines and drapes lower through the span between beams and column lines. Knowledge of these structural differences allows us to accurately differentiate between components. Our Project Managers will leave you feeling confident in our findings and in your ability to drill or cut without issue.
Can GPR determine the difference between rebar and electrical conduit?
Ground penetrating radar (GPR) can accurately differentiate between rebar and electrical conduit in most cases. We have an extremely high success rate in identifying electrical lines in supported slabs or slabs-on-grade before saw cutting or core drilling.
Additionally, GPRS can use EM locators to determine the location of conduits in the concrete. If we can transmit a signal onto the metal conduit, we can locate it with pinpoint accuracy. We can also find the conduit passively if a live electrical current runs through it.
The combined use of GPR and EM induction allows us to provide one of the most comprehensive and accurate conduits locating services available.
