3. June 2024 © Copyright 2024, PROCEQ SA 27
The dielectric constant of concrete can vary widely not only due to moisture content, but also
factors such as the composition of the concrete mix, types of aggregates and the presence of
air voids. This is why it is critical to set ε when considering depth and objects’ size accuracy.
Figure 31: Concrete dielectric ε principle
GP app software provides different solutions to adjust the concrete dielectric.
5.6.4.1 Manual setting of dielectric value
When the concrete dielectric (ε) is known, then the dielectric value can be entered
manually in the image processing menu (see Figure 32).
5.6.4.2 Hyperbola fitting dielectric estimation
When the concrete dielectric (ε) is unknown, then the dielectric can be estimated with
the “Hyperbola fitting” feature. By adjusting the dielectric value in image processing
menu, the user must fit the new appearing yellow hyperbola on any clean hyperbola of
existing object in the raw data view (B-scan) as shown in Figure 32.
Make sure the yellow hyperbola precisely covers-up the object’s hyperbola. Try with
different clean hyperbolas to confirm the concrete dielectric estimation.