×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Non-destructive determination of concrete thickness

Non-destructive determination of concrete thickness

Non-destructive determination of concrete thickness

(OP)
Does anyone know of a non-destrucitve means of determining the thickness of a concrete slab? So far the only means if have found is Ground Penerating Radar (GPR). Is GPR difficult to used and/or interpret? Thanks

RE: Non-destructive determination of concrete thickness

I think GPR (Ground Penetrating Radar) may help. I have used it in the past to detect voids under slabs in an investigation of concrete cracks. Turns out there were a huge void under the slab.

One of the major obstacles in using GPR on concrete slabs is presence of reinforcement.

Contact any GPR lab and ask them directly.

Good luck

RE: Non-destructive determination of concrete thickness

jimrcasper...I agree with Lutfi.  Be sure that whomever does the GPR work uses the correct frequency of antenna for concrete (it is different than for soil).  Determining the thickness of thin slabs is difficult, but with calibration it can be done.  Keep in mind that nondestructive testing only limits the amount of destructive testing/observation that needs to be done....destructive correlation must be done to gain meaningful data.

RE: Non-destructive determination of concrete thickness

Impact echo is good at determining thin slab thickness. I find it easier to interpret than ground radar, particularly if there is a reasonable amount of reinforcing. http://www.ndt.net/index.html has some useful articles and links.

RE: Non-destructive determination of concrete thickness

I would be wary of using only non-destructive methods without any on-site verification.  Would really try to find somewhere inconspicuous where a small hand drill could be used.  Also, once you start getting cost estimates the hand drill option starts looking better and better.

RE: Non-destructive determination of concrete thickness

There is another method called "impact echo".  The following link is a comercially available unit.  Our firm has had some success with this unit provided field conditions are right.

http://www.olsoninstruments.com/ctg/ctg.htm

Good luck
sghvib

RE: Non-destructive determination of concrete thickness

Time to stand on my soapbox for a couple of things:

As I was told when I was in college by my professors, you will need to use your "Engineering Judgment". Boy, were they ever right. I think we all do that few times day.

Not that I am opposed to other methods. I think it all depends on the situation. I agree that expense is an issue. However, if you have a suspicious situation and people safety and client operations and business is on the line, do not go for the cheapest! I have problem with engineers’ who sometimes let economics, or non-qualified sources, blare their sound engineering judgment. Imagine this, you are on surgery table; do you want your surgeon using the cheapest tools and tests!

What is nice a bout GPR you can get 100% coverage of the floor area! It does not take long to scan and the scan width is limited by probe size. The one that I have seen is about 8 - 10 inches wide and the machine travel "like a lawn lower passes and the thermal paper is printed real time. The printout needs to be read and translated to useful data.

Drilling and may give a true picture for very localized.

Use your engineering judgment

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources