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22:21 Jan-05-2010

James Gauthier

NDT Inspector, Operations Manager
GE Inspection Services,
Joined Nov 2007
Concrete Inspection (8ft thick/access one side only)

I am familiar with GPR systems and technology as we have a couple of these units. Good for approx. 3 ft as a rule of thumb (dependent on concrete type and condition). My question is "does anyone know of a way to inspect an 8ft thick concrete specimen that you only have access to one side?"

Impact Echo systems come to mind but I am unfamiliar with the depth capabilities of that particular system. (I think it is similar to the GPR)

Any thoughts?


10:40 Jan-06-2010

Martin Schickert

R & D,
Institute for Materials Research and Testing,
Joined Jan 2000
Re: Concrete Inspection (8ft thick/access one side only) In Reply to James Gauthier at 22:21 Jan-05-2010 (Opening).

The largest thicknesses measured non-destructively I have heard of were in the range of 1.5 to 2 m. We haven't done such measurements ourselves.

Success would depend strongly on the concrete and its surface conditions on both sides. Possible techniques would be ultrasound and impact-echo, using the best equipment and all filtering and averaging possibilities available. To be able to discriminate between back wall echoes and other reflections, I would use line scanning (B-scan) or planar scanning, possibly followed by SAFT reconstruction in the ultrasonic case.

I would be surprised if thickness measurements larger 2.5 m in conrete could be done. If somebody has achieved this, he might drop a note.

Martin Schickert

23:50 Jan-07-2010

Wieslaw Bicz

PBP Optel sp. z o.o.,
Joined Feb 2009
Re: Concrete Inspection (8ft thick/access one side only) In Reply to Martin Schickert at 10:40 Jan-06-2010 .

Based on our experience I would suggest to use bursts with high amplitude and lock-in amplifier. And naturally also some method, that uses synthetic aperture - as already suggested.


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