Non-destructive Testing of Masonry Walls

[Nichole77]

Hello,

I'm not sure where it would be best to post this question...

I was wondering if anyone has had experience with NDT of masonry walls. I am try to do the following:
1. Locate metal wall ties (and possibly size and corrosion). Any recommended pachometers/rebar locators or corrosion mapping equipment?
2. Determine the limits of various materials behind the wall (i.e. if there is an air space, limits of sheathing/waterproofing and flashing). I was looking at ground penetrating radar but wasn't sure how accurate it would be. Also thinking of using a borescope that can measure distance and depth. Any suggestions?
3. Locate areas of moisture penetration using thermography. I was looking at the Flir T440 or T640 but would appreciate any recommendations on thermal imaging cameras for looking at larger areas.

I am trying to find methods that are less expensive (to rent) and can achieve as many of the above as possible with the least amount of equipment.

Thanks in advance!

Nichole

 

[manstrom]

I just used GPR at a slab. It showed bar spacing and depths, but not size. Even still, the owner didn't trust it and we got out grinder and started hacking away.

You may want to start with destructive testing to see what you need to get into.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[Ron]

Nichole...a few points to consider....

First, nondestructive testing only decreases the number of actual holes you'll have to cut in the wall.

For the items you've noted, there is no substitute for selective removal of face brick to expose the wall cavity. From there you can actually see the number, type and spacing of wall ties. You can also get some idea of the integrity of the substrate waterproofing and the necessary thru-wall flashings.

You can use a pachometer to help you locate and plot the spacing of wall ties; however, there is sometimes a lot of interference by horizontal joint reinforcement (ladder type).

Infrared thermography is generally useless for finding moisture in the wall cavity. Besides, any anomalous condition you encounter will need to be verified by cutting into the wall.

If you want to locate vertical rebar in filled cells, you can use ground penetrating radar.

It is not difficult to "surgically" remove a few bricks for observation. We use a diamond bit called a "Glitter Bit" attached to a high speed die grinder. It works great for selectively removing the mortar around bricks without damaging the brick. After observation, you can simply mortar the original bricks back into place.

ALSO!.....it is against forum rules to post the same query in multiple forums. Please delete your other post. This is a more appropriate forum for your question.

 

[Nichole77]

Thank you for the advice! It sounds like nondestructive testing might not be the best way to approach the inspection. I will have to look into the diamond bit. That sounds like the best way to inspect behind the wall without removing too much.

Also, sorry about posting on multiple forums. I can't figure out how to delete my other post and didn't see any "help" links.

Thanks again,
Nichole

 

[Ron]

Nichole...just "red flag" your post and ask management to removed it as a duplicate post. The "Red Flag" link is in the lower right of each post.

 

[darthsoilsguy2]

GPR works great and helps you quickly collect a lot of info and sometimes show you things you didn't know to look for. There are 2 types of GPR i've seen used and i'm not a fan of the cheap one that comes in a toolbox, but the one that looks like a lawnmower is the good one.... Perhaps the problem is person you get working the lawnmower is better at it than the person working the cheaper device.

Hunting for water penetration is a soul-crushing-job of its own.

Because of the variability of rebar position within the core, rebar metallurgy, and laps, i can't think of any good way to corrosion map besides.... "it's here, here, over there, and surely other places unseen too". Joint reinforcing tends to spall out the mortar joint when the corrosion gets bad. Joint reinforcement should be easily found with a pachometer or even a toy metal detector. If you google "Radio Shack Vintage Treasure Finder" you will find a tool i've used that works great for anything under 4-inches of cover for coring when the pachometer was on loan to another office