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CMU consolidation

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Sorry if I have said this before on this list, but my worse experience as an CE was a direct result of pour masonry construction........
 
If your drawings or specs do not require cleanouts at the bottom of every cell they should. If your wall is going up 20ft or so, I would put at LEAST 2, one at mid height. Also require pre-fabricated positioners at designated vertical heights to properly hold the bars in place before and during grouting.
 
Now I don't think ACI 530 is an "enforceable construction document", but it requires cleanouts at the bottom course for each grout pour height over 5ft (S-20, 3.2F). Our drawings are very specific on masonry construction and what is allowed, because masons in FL run the gamut of knowledge and skill level. Even in my short career I have had some nightmare CMU jobs, not due to our drawings either. Especially with 8" block, and depending on the size and amount of reinforcement, it is pretty easy to have some voids in a filled cell even if the cleanout tells you otherwise. Not all masons are out their rodding and vibrating to consolidate. Grout can get hung up on debris, horizontal reinforcement, etc. resulting in void pockets. How good is your CMU wall if all the grout is at the bottom and top of the wall, and the middle of your flexural element is a bar in a hollow cell?
 
Some large retail customers REQUIRE that an infrared camera survey be performed after the CMU is grouted. This will clearly tell you where the voids are. If there is a lot of doubt as to the quality of the consolidation, I highly reccomend it. If I was king for a day, I would highly reccomend to the owner it be done on any CMU job of significance. Imagine the built in QC you get if the mason knows all the CMU will be shot after grouting. Depending on the size of the building, these surveys can cost $1000-$2000....  If you want more information in general check out Stocktoninfrared.com , and if you are in the eastern US I highly reccomend these guys, they do great work and produce great documentation. And no, I do not get a kickback for reccomending them......
 

Andrew kester, PE

LONGWOOD, FL