Saturday Puzzle - CMU Failure 1

[JoelTXCive]

I was out running errands this afternoon and went to the Office Depot near my home.

While walking across the parking lot, I noticed the condition of the CMU wall. See below.......the entire wall is cracked. At first I though it was an architectural treatment of some sort or split faced CMU, but I don't think it is.

It appears to me that the entire wall is cracked. I think the age is about 20 (edited) 30 years.

Do you think this is CMU material failure of some sort? It doesn't look like a foundation issue to me. It seems like a CMU block problem.

What do you think? I've never seen an entire wall cracked like this.

 

[phamENG]

That is odd. It's like a bunch of tightly spaced thermal cracks.

Any chance that's a non-bearing wall with no reinforcement/grout that filled with water that froze?

 

[3DDave]

I think water would tend to blow out sections of wall.

Could there be enough thermal gradient between the heated interior and unheated exterior to cause enough thermal displacement to do this?

Whatever it is it is not localized.

 

[dik]

Control joints seem to be about 30'... not uncommon... no idea of why it would crack like that. Cracking is distributed across the length of the wall.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[BridgeSmith]

Since many of the blocks cracked down the middle, close to or right to the grout joints of the blocks above and below, the only thing that makes any sense to me is that they used some kind of 'mortar' that expands and contracts differently than the block.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[dik]

Is it safe?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[KootK]

Neat, thanks for posting.

Do you think this is CMU material failure of some sort?

That would be my guess. It seems to me that every single block must have been in stalled with an appreciable amount of shrinkage left to do somehow. When that shrinkage was restrained by the horizontal shear connections to the blocks above and below, the cracks developed.

For something like this to happen, I would have to think that you'd need one or both of these things to have occurred:

a) Something having gone awry in the manufacture of the block that rendered it uncommonly prone to post manufacture shrinkage.

b) Install during a period of very high humidity that was followed by a period of very low humidity.

 

[JoelTXCive]

The office depot is open for business. I think the cracking has been there for many years. It appears to me that there have been numerous paint jobs on top of the cracks.

Here's a theory: What if it was a bad batch of CMU blocks with low compressive strength (maybe ~1000psi)? The reduced durability could result in some freeze thaw effects? We get 1-2 hard freezes a year in Houston and they are usually accompanied by rainy weather.

I have to go to PetsMart tomorrow, which is on the other end of the same shopping center building. I'll have a look at the walls on that end.

 

[JoelTXCive]

Here's the location if interested:

https://www.google.com/maps/@29.9586819,-95.5461813,81a,35y,201h,44.9t/data=!3m1!1e3?hl=en

 

[hokie66]

It looks like some of it is painted, some left uncoated. Is there a difference in the amount of cracking? Even acrylic paint will provide some degree of moisture resistance. On the same track, is the cracking the same on all sides?

 

[dik]

They don't look so bad from up here...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[kissymoose]

This brings up a problem we encounter on a regular basis, product certifications for materials like CMU blocks that don't apply to specific products used on site. Very common to see a report from a plant that is years old. Maybe it applies to the blocks used on site after sitting in stock for a while, but probably not. If one batch ended up with a problem, a bad mix, curing time, something that causes problems like those shown here, it could very easily go undetected.

 

[dik]

Unless it was a real mix/batch design problem, I cannot imagine a reason for the cracking to be 8" o/c or thereabouts. The building looks to be too big to do a "walk around", could take half a day to see if the condition is the same on all sides. Are there any other buildings in the same area that have used the same block?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

I've submitted the question to the Masonry Contractors Assoc of America to see if they can offer any suggestions.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[HTURKAK]

Very limited info. to get the reason ..But we are free to guess..

I bet ,

- These are temperature cracks ,

- They did not provide bed joint reinf.

- the construction site engineer was a Smart Civil Engineer.



My opinion..







Not to know is bad;
not to wish to know is worse.

NIGERIAN PROVERB

 

[XR250]

I imagine the wall is mostly unreinforced but if it was grouted with a soupy mix, I wonder if that would be c) on Koot's theory.

 

[JoelTXCive]

The Google Maps team gets an A+ on documenting this shopping center. They mapped the entire shopping center at street view level...

https://www.google.com/maps/@29.957...pHkIixVpcmrOnQy9hZpg!2e0!7i16384!8i8192?hl=en

I also checked Google Earth and the shopping center was built between 1989 and 1995, so the age is about ~30 years.

Also, they are 12" blocks.

 

[dik]

HTURKAK... I don't think they are thermal cracking; they are likely too close... and there may be limited horizontal reinforcing, but that wouldn't account for the cracking in the middle of the CMU. My $.03...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Compositepro]

They look like cracks due to extreme thermo-cycling. Like many years of sun heated walls getting suddenly rained on.

 

[HTURKAK]

Mr. DIK, if you check the pictures that OP posted, the cracks at bottom portion of the wall and diminishes at uppermost section. IMO, the masonry wall constructed on foun. wall or perimeter beam without taking necessary measurements and necessary amount of horizontal reinf.

IMO, The found . wall or perimeter beam ( mostly buried ) has relatively stable temperature but the masonry wall subject to daily temp. variations and sunlight . Most probably this wall is not at northern side of the bldg.

I looked to the International Masonry Institute web site and the following detail..

Not to know is bad;
not to wish to know is worse.

NIGERIAN PROVERB