03 May Ground Penetrating Radar… what’s all the fuss about?
Ground Penetrating Radar, or GPR, gets a lot of focus when on the subject of concrete scanning. So, what’s the big deal?
Yes, we had concrete x-ray prior to GPR – and that technology is still available. But think about the move from dial-up internet to full speed broadband… are you still tying up your home phone line to dial in and read this blog? We didn’t think so.
What is GPR?
Ground Penetrating Radar (GPR) was developed in the 1970s, alongside great discoveries such as the microwave oven and The Rubik’s Cube. Advances made in impulse radar (also referred to as short-pulse radar) saw it being applied to locate the boundaries between soil; and later with expanded applications due to pulse durations being able to be measured in ‘picoseconds.’
What’s one millionth of a millionth of a second?
That’s a picosecond. It’s the measurement of pulse durations in the application of GPR – and what allows it to do things that seem like magic, like see through concrete.
Today, GPR is considered to be an effective geophysical method for non-destructively detecting and investigating the presence and continuity of subsurface objects for a variety of applications. These applications include:
- Concrete scanning or imaging – to gather data about hidden features in concrete structures which could cause issues, damage or harm;
- Underground utility location – to find any hidden power cables and pipes in concrete structures; and
- Other structural investigations which could benefit from non-destructive testing, such as checking structural capacity and establishing suitable core drilling locations.
Why use GPR?
This method of locating hidden nasties in concrete has two main advantages over most other non-invasive geophysical techniques:
- It provides a three-dimensional pseudo-image that can easily be converted to depths that are accurate down to a few centimetres; and
- It responds to both metallic and non-metallic
Additionally, GPR has made its way into the hearts of project managers worldwide due to the following characteristics:
It’s non-destructive – sites can be inspected non-intrusively, allowing structures to be preserved and project down-time to be avoided;
- It’s quick and cost-effective – with real time results that result in little to no downtime, structure damage, or possibility for worker injury.
- It’s efficient – GPR makes it easy to identify safe drill and core locations; and
- It’s safe – GPR technology does not produce any radiation during a scan, so workers and bystanders are protected.
Yes, GPR also has some limitations. Most notably:
- High-conductivity materials, such as clay soils and soils that are salt contaminated, reduce the depth of GPR ground penetration;
- Signals scattering in heterogeneous conditions (e.g. rocky soils) limit performance; and
- Considerable expertise is necessary to effectively design, conduct and interpret GPR surveys;
X-ray vs GPR
GPR technology replaces Concrete X-Ray technology, also known as X-Ray Concrete, X-Ray Concrete Slab or Slab Scan X-Ray. Ground Penetrating Radar delivers more accurate results, is safer to use and provides clearer 2D and 3D projections than Concrete X-Ray technology. GPR also produces images in real time for the concrete scanner technician, making it more efficient and suitable for scanning larger areas.