Masonry Repair?

[SteelPE]

I have a building that is currently under construction that is almost complete (80% at this point). The structure is built in accordance with IBC 2015 and is masonry bearing.

In typical architect fashion, they decided to vary the color of the block to create some fancy architectural accents. The project has been a thorn in everyone’s side with a change in exterior skin from insulated metal panel, to tilt up to CMU. Well during the rendering process, the architect made a mistake along one side of the building with the placement of the color band and it was placed at the wrong elevation. This issue is this color band is correct everywhere else and the GC didn’t question why the color band was placed at a different elevation at this one location.

So the architect is looking to fix this error which occurs along 60’ of perimeter wall. They are looking to remove the face shell of the block and replace it with the proper block face shell (an approximate section 16” wide x 60’long). I am a little hesitant to this repair this because we have a bond beam in this area. The wall is heavily reinforced due to a number of openings in the wall (12" CMU with bars at each face).

Are there any drawbacks into what the architect is proposing (thinking development length, bond between the face shell and the grouted cells etc)?

In 20 years we have never even attempted this type of repair.

 

[JLNJ]

I have not done this nor seen it done.

If you don't need the material of the face shell for stress distribution, then I suppose your structure will be OK. I don't see how you could count on the new face shell to carry load if it's just glued on.

I would think the bigger issue would be the likelihood that the pasted-on face shell stays in place while the wall flexes and does its thing. Especially through freeze-thaw cycles.

 

[SteelPE]

JLNJ,

You are hitting on some of my concerns.

I am concerned about the load bearing of the face shell as well, but I am thinking that under load the face shell is in compression. Therefore it would only need proper bearing to be capable of carrying load.

Freeze thaw cycles are a concern as well. This is in a area where freeze thaw is definitely a concern for the long term serviceability.

 

[jittles]

Just a comment from a different perspective - is the owner on board with getting a "repaired" building rather than the new one they think they're getting?

Or in other words, I would hold this repair to a very high standard before accepting. I'd absolutely want somebody experienced with this specific repair guiding the process/spec/installation.

 

[phamENG]

Look into polymer modified mortars. They are intended for spall repairs, which isn't completely unlike what you're doing. I don't have experience with them, but have come across them in various trips down the structural engineering rabbit hole. Whether or not they will develop sufficient strength to bond a new face shell to the grouted core or not - I don't really know.

 

[KootK]

How tall is the wall and how high up is this band?

This gives me the heebeejeebees but, anecdotally, don't face shells normally get removed and reconstituted as part of the cleanout business?

 

[phamENG]

KootK - for high lift, yes. But that's typically one face every 2 to 5 feet. So you can count on the remaining shells around it. If you're doing high lift, you can plan it to keep your compromised face shells away from high stress areas.

If the rebar is too dense, high lift isn't a good idea anyway (even though nobody likes having to have an inspection every 5'4").

 

[SteelPE]

KootK,

This is a very tall wall.

The architect is pressuring me to accept the proposed repair. As far as I know, clean outs are just in a cell... and every 40" o.c. or so..... and the repair is grouted in place. This is a 43'-4" long section of wall that will have 16" of face shell removed. It's not a small area. So I get the argument, but not I don't buy it in this instance.

The only thing I have going for me is the repair is close to the top of the wall.... meaning the bending load in the wall (no axial load as it's a non bearing wall) are reduced somewhat.

I have heard every excuse from them at this point...... I want to help them out, but this building is riddled with QC issues (missed bearing plates, misplaced bearing plates, leaning walls all from a limp wristed site super) I don't need to add anymore to my plate.

 

[KootK]

Yeah, I realize that clean outs are much intermittent than what we're discussing here. But, still:

1) It's not like anybody's omitting cross section to account for clean outs in design and;

2) To my knowledge, the restored face shells of clean outs are not popping off in the winter. In my opinion, it is the durability aspect of this that is the most important. Ergo, I consider the absence of durability issues in the clean out condition to be a good sign.

The only thing I have going for me is the repair is close to the top of the wall.... meaning the bending load in the wall (no axial load as it's a non bearing wall) are reduced somewhat.

I would say that your only thing is a very important thing. With no axial and minimal bending, you're down to durability and shear capacity, both of which are probably manageable.

I want to help them out, but this building is riddled with QC issues (missed bearing plates, misplaced bearing plates, leaning walls all from a limp wristed site super) I don't need to add anymore to my plate.

I'd be inclined to help them out in this instance. I doubt that it will cost you anything and, you know, clients do like being helped with stuff. In my opinion, there should be no punitive aspect to contract administration.

 

[phamENG]

What does the site look like? Where the offset bands meet, is there a large viewing area for it? If not, you could use that in defense of doing nothing.

Had one recently where the "cast stone" lintels were installed at the wrong elevation in the side wall of a building. Fortunately it was just an opening so it was functionally ok. But it didn't match the other walls. We determined that the only person who would reasonably notice it was the guy who parked in a particular parking spot, so the arch let it go. Granted, the lintels weren't touching at the corner, so it wasn't as bad visually anyway.

 

[SteelPE]

KootK,

Not trying to be vindictive or anything... just imagining court proceedings (like I always do) where I have already taken on additional liability from what I originally signed on to take on. If this building was a year it would be 2020.

 

[SteelPE]

PhamENG,

Currently you stare at this section of the building when you drive in. There is a new entrance for the building... but this building is behind another and you can't see it from the street.

 

[r13]

From the reading of several posts of yours, It seems you were "pissed off" by your architect in many occasions, maybe something needs to change...

 

[jittles]

I have heard every excuse from them at this point...... I want to help them out, but this building is riddled with QC issues (missed bearing plates, misplaced bearing plates, leaning walls all from a limp wristed site super) I don't need to add anymore to my plate...

...If this building was a year it would be 2020.

Oh, this is still that building... I've seen some of your other posts and I do not envy your position. I hope you are remembered as the great consultant that helped solve problems that were created by others, and not have your name simply attached to a project riddled with issues.

 

[EZBuilding]

I think the big difference between the clean-out example and the proposed repair detail is that the clean out face shell gets filled solid with grout. In this repair, you're going to get a face shell slapped on to the remaining masonry wall.

If I were to start looking at the repair I would start by reviewing strength and deflection provisions ignoring the face shell from participating. After that I would probably chew on it a bit more...

 

[r13]

Spalling is a real concern/threat, especially something up high.

 

[KootK]

I think the big difference between the clean-out example and the proposed repair detail is that the clean out face shell gets filled solid with grout.

It had never occurred to me that someone might attempt the repair without also grouting the cells behind the repair. If that's the case, then maybe a good solution here is to have those cells grouted as part of the repair. That seem entirely reasonable to me.

I was lead to believe that there was a bond beam in the vicinity of this repair band.

 

[KootK]

Another thing to consider in the weighing of this: with two layers of reinforcing in a low moment region, you probably don't even require any masonry participation for your flexural resistance. You know, other than that flexural usually necessitates shear resistance.

 

[r13]

I am a little hesitant to this repair this because we have a bond beam in this area. The wall is heavily reinforced due to a number of openings in the wall (12" CMU with bars at each face).

Will this statement help, or change mind?

 

[Rabbit12]

Could you "glue" glazed CMU faces to the existing block? We had a project recently where the contractor was having trouble getting full glazed blocks (long lead time) so they just bonded shells to the face of CMU.

I'm with you, I don't like the idea of tearing the face off the existing blocks. You don't hear about cleanouts popping off, but what happens when one of yours does and hits someone?