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- since 1996 -

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Technical Discussions
Chris Barnes
R & D
Dalhousie University, Canada, Joined May 2002, 6

Chris Barnes

R & D
Dalhousie University,
Canada,
Joined May 2002
6
00:38 Sep-03-1998
Detecting Voids in Voided Post-Tensioned Concrete Decks

Would anyone be able to give me assistance in contacting
an expert/company, preferably in Eastern Canada, who
has experience detecting voids in post-tensioned concrete
bridge decks? Apparently, due to the use of concrete
that was late in arriving on site, inspectors suspect
the occurrence of large entrapped air voids in the deck.

Is UT the best test method for detecting these voids?
Who in Eastern Canada has considerable experience with
detecting such problems using UT?

Thanks in advance,

Chris Barnes



    
 
 
Jeff deWalle
Jeff deWalle
01:09 Sep-05-1998
Re: Detecting Voids in Voided Post-Tensioned Concrete Decks
Our company has a system to inspect concrete for voids, cracks and thickness.
Please call me at 416-213-8000 in Toronto



    
 
 
M. Krause
R & D
BAM Berlin, Germany, Joined Nov 1998, 1

M. Krause

R & D
BAM Berlin,
Germany,
Joined Nov 1998
1
06:05 Sep-10-1998
Re: Detecting Voids in Voided Post-Tensioned Concrete Decks
We have experience in detecting voids in tendon ducts using ultrasonic echo
methods and 3D-SAFT reconstruction calculations.
Up to now our results are from experiments on
test specimens in the laboratory.

Some results are published in www.ndt.net (ut-online
1997 No 5, M. Krause. H. Wiggenhauser, Ultrasonic
Pulse Echo Technique for Concrete Elements), and an
overview of a round robin test is published in: Structural Materials Technology III, An NDT Conference,
SPIE Volume 3400, 1988, p. 258 - 269 (J. Krieger, M. Krause, H. Wiggenhauser,
Test and assessments of NDT methods for concrete bridges).,

Areas of concrete with internal compaction faults can be localized using
a transmission method, when the concrete element is accessible from both
sides (see e.g: A. Roesch, B. Hillemeier, E. Porzig, M. Krause, C. Maierhofer,
Air voids, poor compaction and areas of low concrete stregth detection in concrete
by pulse velocity maesurements, in G. Schickert, H. Wiggenhauser(eds), Int. Symp. on
Nondestructive Testing in Civil Engineering (NDT-CE) Vol 2, DGZfP,
Berlin 1995, pp 895 - 902 (ISBN 3-931 381-02-1).
: Would anyone be able to give me assistance in contacting
: an expert/company, preferably in Eastern Canada, who
: has experience detecting voids in post-tensioned concrete
: bridge decks? Apparently, due to the use of concrete
: that was late in arriving on site, inspectors suspect
: the occurrence of large entrapped air voids in the deck.

: Is UT the best test method for detecting these voids?
: Who in Eastern Canada has considerable experience with
: detecting such problems using UT?

: Thanks in advance,

: Chris Barnes





    
 
 
Chris Barnes
R & D
Dalhousie University, Canada, Joined May 2002, 6

Chris Barnes

R & D
Dalhousie University,
Canada,
Joined May 2002
6
09:22 Sep-10-1998
Re: Detecting Voids in Voided Post-Tensioned Concrete Decks
Dear Colleagues,

Thankyou very much for the prompt and informative
replies to my query. I have received suggestions on
both ultrasonic testing and on impact echo methods.
Which is more rigorous and/or reliable?

I understand that impact echo testing produces 3 wave
types through the medium, 2 of which, R-waves and P-waves,
may be used to compute pulse velocity and for detecting
and locating voids/cracks/flaws. Also, this technique
requires access to only one exposed face of the concrete
target and does not need a surface-transducer couplant.

Is ultrasonic testing, for detection and location of flaws,
limited to through-transmission types of tests where
transducers are applied to opposing faces of a concrete
element? Are ultrasonic transducers powerful enough to
produce and detect multiple reflections of a pulse such
that thickness may be determined by frequency analysis
methods?

Is one method superior to the other for concrete deck/element
inspectionpurposes?

Yours very truly,

Chris Barnes


    
 
 
hongyao sun
hongyao sun
01:58 Jan-10-2001
Re: Detecting Voids in Voided Post-Tensioned Concrete Decks
: We have experience in detecting voids in tendon ducts using ultrasonic echo
: methods and 3D-SAFT reconstruction calculations.
: Up to now our results are from experiments on
: test specimens in the laboratory.

: Some results are published in www.ndt.net (ut-online
: 1997 No 5, M. Krause. H. Wiggenhauser, Ultrasonic
: Pulse Echo Technique for Concrete Elements), and an
: overview of a round robin test is published in: Structural Materials Technology III, An NDT Conference,
: SPIE Volume 3400, 1988, p. 258 - 269 (J. Krieger, M. Krause, H. Wiggenhauser,
: Test and assessments of NDT methods for concrete bridges).,

: Areas of concrete with internal compaction faults can be localized using
: a transmission method, when the concrete element is accessible from both
: sides (see e.g: A. Roesch, B. Hillemeier, E. Porzig, M. Krause, C. Maierhofer,
: Air voids, poor compaction and areas of low concrete stregth detection in concrete
: by pulse velocity maesurements, inG. Schickert, H. Wiggenhauser (eds), Int. Symp. on
: Nondestructive Testing in Civil Engineering (NDT-CE) Vol 2, DGZfP,
: Berlin 1995, pp 895 - 902 (ISBN 3-931 381-02-1).
: : Would anyone be able to give me assistance in contacting
: : an expert/company, preferably in Eastern Canada, who
: : has experience detecting voids in post-tensioned concrete
: : bridge decks? Apparently, due to the use of concrete
: : that was late in arriving on site, inspectors suspect
: : the occurrence of large entrapped air voids in the deck.

: : Is UT the best test method for detecting these voids?
: : Who in Eastern Canada has considerable experience with
: : detecting such problems using UT?

: : Thanks in advance,

: : Chris Barnes





    
 
 

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