×
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

Ground Penetrating Radar?

Ground Penetrating Radar?

Ground Penetrating Radar?

(OP)
I am trying to perform a non destructive testing of a building shear wall which is about 20" thick.  I was thinking of using GPR (ground penetrating radar) to do the probe. Due to congestion of reinforcing in the wall, I am giving second thought to this GPR, as it will be unable to descern closely spaced reinforcing and reveal the delamination behind them!

Can you guys point me to any other NDT methods that can reveal any structural imperfection in this wall under these circumstances?

Thanks in advance.

RE: Ground Penetrating Radar?

Thermography might work. I've used it in the past on bridge decks - works very well. I've never used it on a wall but I know it can be done. We were going to use it for a retaining wall inspection. I've heard of building thermography but don't know anything about it.

Keep in mind, thermography won't show the reinforcement only the delaminations but not the depth, and the surface needs to be exposed to sunlight for a few hours. There's a firm in Milwaukee that I've dealt with in the past.

You can use an x-ray but I wouldn't recommend it. There are too many safety concerns to deal with.

RE: Ground Penetrating Radar?

Ultrasonic Testing (UT) may be an option.

RE: Ground Penetrating Radar?

(OP)
Not too sure about ultrasonic, feels like the received wave may be too distored due congestion of reinforcement and thickness of the wall! Am I right?

RE: Ground Penetrating Radar?

(OP)
Meant to write 'distorted'-sorry.

RE: Ground Penetrating Radar?

We're looking a GPR to locate underground facilities on a refinery.  Try geomodel.com, bloodhoundunderground.com or thompsonengineering.com.  They may have a recommendation.

RE: Ground Penetrating Radar?

Impact echo should pick up delam, other methods for picking up reo.  What imperfections are you looking for?  There is nothing that does everything.

RE: Ground Penetrating Radar?

(OP)
I am perticularly interested in voids behind surface, concrete to steel delamination, etc.

RE: Ground Penetrating Radar?

The best bet for this application by far is impact echo. GPR (with a 1.5 GHz antenna) has difficulty penetrating reliably beyond about 18 in., particularly with the two mats of steel. Infrared thermography could work to identify front side delaminations, but no way could you see back side delams in a 20 in. wall.

IE would work in the hands of a seasoned NDE engineer, as reflections from a backside delam would be indicated as a thinner section of wall. Areas where the wall is say 15 in. would likely indicate a delam. As always with any NDE methodology, confirmational testing (coring, drilling, etc.) is recommended.

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