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570 views
00:01 Oct-29-1999

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1208
Ground Penetrating Radar

In the past two days there have been questions asked relating to
examination of concrete structures and ice thickness.
Most of us in NDT assume this type of thing to be in the realm of
Low Frequency UT. However, Ground Penetrating Radar may be the
best option we have available.
GPR can be and has been used for:
-deep geological definition
-karstic mapping
-survey frozen lakes & rivers by truck of snowmobile
-glaciology studies
-locate groundwater
-locate metal and plastic anc concrete pipes
-locate rebar
-define roadbed sumping
-examine bridge structure integrity

The software used can collect data and display it in a
format we in UT would call a B-scan.

The depth of the penetration and the resolution possible are
dependent on the "antenna" size and frequency used.

For more information and other links there is a website :
http://www.sensoft.on.ca/

Ed




 
04:02 Nov-03-1999

Chris Barnes

R & D
Dalhousie University,
Canada,
Joined May 2002
6
Re: Ground Penetrating Radar Hi Ed,

I am not sure if GPR may be the best method for detecting the cracks that may have developed in earthquake damaged buildings. In my own experience, GPR has been useful for detecting corrosion related problems in bridge decks by finding areas of moisture and chloride ingress in the deck. This is based on signal attenuation due to increased conductivity from the moisture and chloride. Detection of actual cracks is more difficult, especially since most cracks are less than a millimeter in width - which tend to produce very small changes in the reflected signal (depending on the frequency used of course). Add the increased complexity of real structures, materials and construction to this and it is unlikely that cracks can be found in a practical setting. Does anyone else have any comments to add to this?

Regards,

Chris Barnes


: In the past two days there have been questions asked relating to
: examination of concrete structures and ice thickness.
: Most of us in NDT assume this type of thing to be in the realm of
: Low Frequency UT. However, Ground Penetrating Radar may be the
: best option we have available.
: GPR can be and has been used for:
: -deep geological definition
: -karstic mapping
: -survey frozen lakes & rivers by truck of snowmobile
: -glaciology studies
: -locate groundwater
: -locate metal and plastic anc concrete pipes
: -locate rebar
: -define roadbed sumping
: -examine bridge structure integrity

: The software used can collect data and display it in a
: format we in UT would call a B-scan.

: The depth of the penetration and the resolution possible are
: dependent on the "antenna" size and frequency used.

: For more information and other links there is a website :
: http://www.sensoft.on.ca/

: Ed




 


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