Existing CMU - Determining Reinforcing
Existing CMU - Determining Reinforcing
(OP)
What is the easiest way to determine the composition of an existing cmu wall? Making a few holes through the face seems like an easy way to determine grouting but what about the reinforcing? I would like to avoid GPR or anything too complicated. I have fairly limited access and need to be as nondestructive as possible.
thanks
thanks






RE: Existing CMU - Determining Reinforcing
RE: Existing CMU - Determining Reinforcing
RE: Existing CMU - Determining Reinforcing
It rolls over the surface of the wall, and will produce rebar size (i think to within 1/8" diameter) as well as depth in the wall.
You may be able to rent them.
RE: Existing CMU - Determining Reinforcing
RE: Existing CMU - Determining Reinforcing
One possible drawback to a magnetic scanner, pacometer, whatever you wish to call it, on a masonry wall could be that while you may be able to pick up the reinforcing, you may very well pick up on the wire reinforcing placed between the CMU blocks embedded in the mortar, which may give you a false reading.
Also, reinforcing at door locations and wall joints are usually doubled up, but the scanner will only accurately pick up that reinforcing is there, not how much reinforcing...if it doesn't pick up on the door jamb.
Short of mini-drilled holes spaced at a certain preset on center (32" or 48", usually), other methods could be considered a best-guess scenario.
RE: Existing CMU - Determining Reinforcing
Clarke Engineering Services, PC
Construction Consulting & Anchor Testing
www.anchorengineer.com
RE: Existing CMU - Determining Reinforcing
This brings up another question which is unrelated - I am having them reinforce and grout all the areas where I am involved in new work. I have recommended to the arch. that they grout/reinf cells for the remainder of the wall but I don't think this will happen. There is no way this wall "works" as is but it obviously is working... what is my responsibility beyond suggesting they do further work beyond what I am involved in?
RE: Existing CMU - Determining Reinforcing
I used to inspect bridges in NYC. There were holes in walls (not meant to be there) that I could walk through. I was young and couldn't understand how it was still standing. yet there it was! We are so trained to think that concrete and masonry will not stand without steel... but Rome did pretty well for a while
There are variences allowed for rehabiliting old structures where you can design under the older codes. Give the DoB a buzz or check their website which is pretty good..
Clarke Engineering Services, PC
Construction Consulting & Anchor Testing
www.anchorengineer.com
RE: Existing CMU - Determining Reinforcing
If you are working under the above code, I suggest you read chapter 34 very carefully. It can be interpretted that you own the entire structure if you make even a small modification to a seismic force resisting element.
RE: Existing CMU - Determining Reinforcing
When ispecting CMU structures, a rebar scanner is something you should have in your hip pocket. I picked up mine at ACE hardware 15 years or so ago, and it works just fine. Saved my a** a once or twice too.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Existing CMU - Determining Reinforcing
Clarke Engineering Services, PC
Construction Consulting & Anchor Testing
www.anchorengineer.com
RE: Existing CMU - Determining Reinforcing
As for your structure, if you believe it is a safety issue for the occupants then it is your responsibility to notify the owner of the conditions and/or defects. (I do not work in seismic country so I am not that concerned with seismic force resisting elements).