Masonry Cleanouts 1

[SteelPE]

I have a building that is currently under construction that I am quite miffed about. The building is utilizing some CMU stair shafts as shear walls. We are grouting the walls solid and have give the contractor the option to do low lift grouting or high lift grouting. The contractor selected the use of high lift grouting.

During my last visit to the site, the CMU walls were being constructed and had yet to be grouted. I commented and noted in my field report that since high lift grouting was being utilized that cleanout holes would be at the bottom of the CMU would be required. The contractor complained but I told them the information was clearly on the drawings and they were the ones who selected high lift grouting for their ease.

Fast forward to my field visit today, when grouting of the CMU walls was complete... with not a cleanout hole on the entire project.

I am not sure what to do in this instance. Very angry right now.

 

[jayrod12]

Make them pay for a GPR or similar test to prove that the wall is fully grouted with no voids. Otherwise they're welcome to remove and re-install properly according to the specs.

 

[phamENG]

@jayrod12 nailed it. There are ways to prove it was grouted. None of them are cheap.

 

[Jrit]

We had a project several years ago that had a CMU issue. They performed an infrared scan with a ThermaCAM T420, and it perfectly showed which cells were grouted. Not sure of cost or who paid.

 

[SteelPE]

Is it just a matter to prove that it is grouted? I was always understood the requirement for cleanouts as to clean out the mortar droppings from the bottom of the grouted cells to allow for proper bonding of the grout to the concrete wall/grouted lift. The mortar droppings will be in hardened clumps with various voids throughout the base of the lift...... not really a good situation.

 

[XR250]

@jayrod12 nailed it. There are ways to prove it was grouted. None of them are cheap.

Then what do you do when you find the inevitable voids? Fun analysis.

 

[jayrod12]

Then what do you do when you find the inevitable voids? Fun analysis.

Sounds like it's a contractor problem to fix at that stage no? Pressure grouting is a reasonable solution in my mind. One hole at the bottom of each void, one at the top, pressure grout in the bottom until it comes out the top. Rinse and repeat as necessary at each void.

Is this going to be painful, absolutely it is. But such is life sometimes when you don't follow directions.

 

[JoshPlumSE]

Honestly, I feel like this (having grout clean outs) is standard practice that most experienced contractors should have caught really early on.

I haven't worked on very many masonry projects. But, I did do a couple of remodels of existing older building were we used GPR to determine grouting and reinforcement spacing. No one was really worried about that cost, though I don't know the actual numbers.

At this point, that GPR is (IMO) a good solution for everyone. Or, any form of non-destructive testing.
a) It's probably not all that expensive when compared to other options at this point. There are companies that specialize in this sort of thing and seem to be pretty good (and quick) with their work.
b) It will demonstrate how well they did the grouting. If they did a great job, they are vindicated. But, they still should foot the bill for this cost.
c) The owner (and you the engineer) can rest easier knowing you've really got.

I'm wondering what happens if (or when) voids are detected. Are there less intrusive methods to solve this problem other than busting open the wall wherever you find them. Like making smaller grout holes only where the voids are detected?

 

[phamENG]

Are there less intrusive methods

Yes. jayrod mentioned one above. Drilling small holes and setting an injection port in the lower one, they pump grout in under pressure. when it squirts out of the hole at the top, you know the void is full.

 

[emmgjld]

The bottom of the grouted columns could be cored. If too much debris, cleaned out and dry-packed.

 

[gte447f]

Is this a commercial building? Are Special Inspections per IBC Chapter 17 not required? SteelPE, are you performing the Special Inspections? If not, what has the Special Inspector reported for verification of the grout space prior to grouting? Special Inspections, which are really sort of a pain in the neck, are supposed to catch stuff like this.

 

[GC_Hopi]

Is it just a matter to prove that it is grouted? I was always understood the requirement for cleanouts as to clean out the mortar droppings from the bottom of the grouted cells to allow for proper bonding of the grout to the concrete wall/grouted lift. The mortar droppings will be in hardened clumps with various voids throughout the base of the lift...... not really a good situation.

Have them cut on the face on a number of the cells at the bottom of the wall to prove there is minimal droppings. If they find some then cut all cells with rebar. Is this partially grouted? Or go straight to check all the cells that have bar. What is your comfort level... at this point they bear the responsibility to prove it will work so put as much of a burden on them as necessary to prove out the design.

 

[SteelPE]

Special inspections were specified and outlined in a Special Inspections Document we issued to the owner prior to construction.

Now it appears as if everyone is onboard with regards to doing things correctly (at least they say they are). In brushing up my cleanout knowledge, I have come across S3.2F of the masonry code (I hope that is the right reference) that states:

Provide cleanouts in the bottom course of masonry for each grout pour with the grout pour height exceeds 5'-4"

1. Construct cleanouts so that the space to be grouted can be cleaned and inspected. In solid grouted masonry, space cleanouts horizontally a maximum of 32" o.c.
2. Construct cleanouts with an opening of sufficient size to permit removal of debris. The minimum opening dimension shall be 3 in.
3. After cleaning, close cleanouts with closures braced to resist grout pressure.

These walls are solidly grouted..... so by letter of the code, cleanouts only need to happen at 32" o.c. (or every 4th cell). Is there a reasoning for this? Does this imply, if we were to test the bottom of the cells, that we would only need to check cells@ 32" o.c.?

 

[gte447f]

Does this imply, if we were to test the bottom of the cells, that we would only need to check cells@ 32" o.c.?

This sounds reasonable to me.

 

[phamENG]

I'm pretty sure the 32" maximum spacing is looking at locations where you have a bond beam or a lintel at the bottom of the pour. Everywhere else, you'd need it at each cell that gets grouted because you need to be able to remove the broken mortar fins and other debris wherever you put grout.

Since this is an after-the-fact test, you might use 32" as your baseline, but I'd certainly go with every reinforced cell as that is where grout is likely to be most critical. But before going in, set limits. At what point do you stop and scan the whole wall? 1 obstruction/void? 2? 10% of the wall?

 

[GC_Hopi]

I think thermal scanning or gpr is a given then throw cutting open cells on top of that as engineering judgement and for piece of mind.

 

[GC_Hopi]

Probably some items to consider when deciding what cell to cut open are which would happen after the scans.... dimensions of the wall and height of the wall to make a judgement on what frequency in plan and elevation would given you a representative sample. Also, stress in the CMU so you can check any critical areas.

 

[SteelPE]

So at this point, we are going to have them verify grouting at all cells with reinforcing. In addition, where the walls are part of the LFRS for the structure, we are going to have them verify all grouted cells.

In addition, at locations were the walls are part of the LFRS, I am going to have the contractor pop off two face shells at random locations to "put some eyes" on what it looks like down there.

It may be perfect down there.... but that should be verified by testing and visual observation.

 

[gte447f]

So at this point, we are going to have them verify grouting at all cells with reinforcing. In addition, where the walls are part of the LFRS for the structure, we are going to have them verify all grouted cells.

Verify by what method? Just curious.

 

[SteelPE]

They ended up verifying the cells using GPR.... which wasn't a big deal and only took a few hours. They said they have to come back and verify the construction once the grout is fully cured.