26. February 2024 © Copyright 2024, PROCEQ SA 9
1.4 Product applications
Structural assessment with the PD8050 is typically done for the following cases:
1. Thickness measurement – e.g. tunnel lining thickness.
2. Verification of the presence or absence of structural defects, in particular voids,
delaminations and honeycombs.
3. Verification of the presence or absence of voids inside tendon ducts.
4. Concrete quality assessment by means of ultrasonic pulse velocity measurements.
In all cases, a good starting point is the recommended measurement settings.
Case 1 – It is important to know the expected thickness of the tunnel and select the
appropriate depth of field. This will usually be the intermediate range. Because of the large
amount of reinforcement used in tunnels, it is typically not advisable to use the near field setting
as this has a reduced transmission voltage.
Case 2 – For this investigation it is necessary to find out as much information as possible
on the suspected defect. Are there drawings of the structure available? How thick is the
structure? What kind of defect is suspected? (e.g. a void caused by concrete not flowing freely
due to dense reinforcement). Is the approximate depth of the suspected defect known? Have
any destructive tests been carried out to confirm the presence of a defect? Once this is known,
the starting point is to try and locate a position on the structure where there is a backwall echo
clearly visible and then compare this with the images taken at the suspected defect locations.
Case 3 – This technique involves locating the tendon duct with a GPR instrument and then
carrying out a full 3D matrix scan along the duct to look for variations in amplitude which
indicates the likely presence of voids. There are several guidelines available on this technique
that the user is advised to consult for further information.
Other than case 3, the best way to proceed is to try and detect a clean backwall image at some
point on the structure.
Case 4 – In this case it is necessary to know the thickness of the element being tested
and to set the appropriate depth of field.
To Next Page
Loading...