26. February 2024 © Copyright 2024, PROCEQ SA 78
10 Frequently asked questions
Is it possible to detect grouting defects in tendon ducts with ultrasonic pulse echo?
Ultrasonic pulse echo is one of the only technologies that can detect grouting defects in tendon
ducts. The technique is based on variations in the amplitude detectable in grouted and non-
grouted sections. Fully grouted ducts give a partial reflection. Non-grouted sections give a total
reflection.
Is it possible to measure steel fiber-reinforced concrete with ultrasonic pulse-echo?
Yes. Unlike electromagnetic methods such as those employed by GPR and cover meters,
which do not work on steel fiber-reinforced concrete, ultrasonic pulse echo is well suited for
measuring this material. It has been successfully used for detecting voids, detecting cover
depth to rebars and pipes, and also for determining the thickness of shotcrete layers.
Is it possible to combine multiple 3D matrix scans in the Pundit Live Array app?
With the Pundit Live Array App, you can create a single 3D matrix scan limited to 1.5m in
length. If you wish to combine multiple 3D matrix scans to create a wide-area 3D image, this
can be done using the Pundit Vision software. The Pundit Vision software also allows the
combination of orthogonally collected 3D matrix scans to create the most detailed images
possible using ultrasonic pulse-echo technology.
Is it possible to detect water-filled voids with ultrasonic pulse echo?
Yes, it is possible to detect water-filled voids. One of the reasons that shear waves are used
in the Pundit PD8000 instruments is that in comparison with P-waves (compression waves),
they are better suited to detecting water-filled cracks and voids.
Is it possible to detect voids below rebars using ultrasonic pulse echo?
Yes, ultrasonic pulse echo is the correct technology for detecting voids, honeycombs, and
delaminations below the rebar grid. Whereas a dense rebar structure will block a GPR signal
from penetrating deeper into the structure, an ultrasonic pulse echo signal is only partially
reflected. The signal that passes through is able to detect deeper-lying voids.
Are there any standards for pulse echo testing?
Pulse echo testing is included in the European standard EN 12504-4 for pulse velocity
determination. This is then subsequently included in the standard EN13791 for in-situ
compressive strength estimation. The application is also covered in several guidelines. The
most comprehensive of these is the German Society for Non-Destructive Testing Guideline
B4. It is also covered in a German highway authority guideline for measuring tunnel lining
thickness (ZTV-ING Teil 5 Tunnelbau) and ACI 228.2R.
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