Garage Pad pour issues... Advice needed!

[g1teg]

Hi All!

I hired a company to do my pour. I did an 8" slab, in floor heat, with an 18" thickened edge footing.

32 MPa, 5-8%. Pour took about 3 hours, and the crew finished the floor (smooth) for about 3 additional hours. They were good, hand screeded, hand trowel, then finished with a couple different pads on the power trowel.

it was a pretty cool day. 68F as the high. Pad was nearly completely in the shade when the guys finished. We wet it lightly and they told me to wet it a few more times that night, and again in the morning.

Today when I got home from work (~26 hours after they finished), I saw some cracks, which I was fine with, but as I walked on it, I could hear crunching. Tapping on the floor in most spots feels hollow, and some of it was moving considerably. I think about 1/8" on top has separated over most of the pad.

See pics. What can be done? What should I expect them to do? Right now, theyre claiming maybe it was bad concrete from the supplier.

 

[Countyroadtrailers]

Wow....who had the supplier come, them or you?

If they ordered it I'd say it's still their problem. Gets to be a gray area if you did. I'd definitely be saving the delivery receipts from the concrete trucks either way.

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[carnutdallas]

Got to grind it off and see what it is like below. That super *****. I have never heard of wetting again after it is is finished off. I have never been told to do that!?! I am a construction neophyte, but my concrete guy has done several projects for me and I have been a part of several commercial builds and never ever seen or been told that. Keep us posted.


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[KnurledNut]

Did they add a bunch of water to the top when power troweling?

 

[g1teg]

Their GC ordered the concrete, though only 1 of 2 trucks left a receipt.

They added a tiny bit of water, you can see the water bottle in his hand, a squirt here and there was all really...

 

[The Cobbler]

I don't think wetting the concrete before it hard set did you any favours, nor did the water bottle they used to finish. sounds like a botched pour in my opinion. sorry

 

[Plastikosmd]

This was a good quick read as I googled issues for my own knowledge of your problem
https://www.cement.org/docs/default...auses-prevention-repair.pdf?sfvrsn=4&sfvrsn=4


Sounds like delamination, less likely blisters based on pic??

 

[g1teg]

This was a good quick read as I googled issues for my own knowledge of your problem
https://www.cement.org/docs/default...auses-prevention-repair.pdf?sfvrsn=4&sfvrsn=4


Sounds like delamination, less likely blisters based on pic??

Sounds exactly like delamination in that article, thanks! I only tapped with my fingers to expose that hole...!

So botched pour/bad surface finish... Will grinding and sealing be sufficient? Repour the whole thing?!?

This is the only part of the entire job I'm paying for professionals!

 

[like2wheel]

I know nothing about concrete, but this recent thread seems similar:

https://www.garagejournal.com/forum/showthread.php?t=430454

I'd wait for LLwillysfan to chime in

 

[g1teg]

Reading about delamination, it's definitely that.

The causes all add up. Vapour barrier, cold subgrade (started early after a cold night), thick slab (8-18" depth) sun exposure during the pour, windy day and air entrainment!

I'm feeling sick, glad I haven't paid for it yet!

 

[KnurledNut]

Did they bull float it after screeding?
When they hand troweled (before power troweling) did they use steel trowels or mag floats?
Steel traps the bleed water and air to early.
Also, over troweling can cause spalling.

 

[g1teg]

Did they bull float it after screeding?
When they hand troweled (before power troweling) did they use steel trowels or mag floats?
Steel traps the bleed water and air to early.
Also, over troweling can cause spalling.

I'm not 100% sure to be honest. I *think* screed, to mags around the perimeter at least, and then steel, then power trowel.

 

[bdk1976]

Holy **** that is bad. I vetted my concrete guy like I was a PI and was still worried sick when the first truck rolled up. Like you, this is the only thing I hired out.

You might still have some leverage if you haven't paid, IMO, but might not be a pretty fight. Best of luck and let us know how this works out.

 

[g1teg]

Holy **** that is bad. I vetted my concrete guy like I was a PI and was still worried sick when the first truck rolled up. Like you, this is the only thing I hired out.

You might still have some leverage if you haven't paid, IMO, but might not be a pretty fight. Best of luck and let us know how this works out.

Thanks, I went through a few first, and this crew came highly recommended! They clearly cared about the job. I was very happy until tonight.

I'm also not worried about the strength beyond the surface, and if they can fix this, I'll be fine... I just want to be sure it's not a patch job just to get paid and I'll be back here in a year.!

All the prep, insulation, forms, steel and heating I did... They just poured/finished it.

 

[James-W]

WOW, that is not good. I am not sure what the best course of action is. If it were me, i would prefer it to be ripped out and do it over. But you have to know full well the concrete guys are not going to want to do that. It would likely turn into a court case and I suspect you will win. Problem is, it would no doubt be a long time before the case even gets to court and that means your project will be held up for quite some time.

I suppose you could have it ripped out and re-poured by another concrete crew and then take the first concrete crew to court and sue for damages and the cost of ripping out the "bad pour" but again, this could take quite awhile to get to court and it isn't 100 percent certain you would win. I really don't know what to suggest.

 

[joes169]

Not sure this one can be blamed on the finishing crew if they didn't order the concrete. Whoever decided to order up to 8% air entrainment for a power trowelled floor holds the most responsibility, imo, especially with a strong wind.

I know a lot of folks here suggest doing exactly what you did, all of the prep yourself and then hiring a good concrete crew to pour and finish. This is one of the downsides of doing so, though, as it often spreads the liability to several parties, creating murky waters.

I personally contract several hundred yards of power troweled floors out every year, there's no way I'm allowing anyone else to decide what concrete mix I'm going to warranty.

 

[g1teg]

Not sure this one can be blamed on the finishing crew if they didn't order the concrete. Whoever decided to order up to 8% air entrainment for a power trowelled floor holds the most responsibility, imo, especially with a strong wind.

I know a lot of folks here suggest doing exactly what you did, all of the prep yourself and then hiring a good concrete crew to pour and finish. This is one of the downsides of doing so, though, as it often spreads the liability to several parties, creating murky waters.

I personally contract several hundred yards of power troweled floors out every year, there's no way I'm allowing anyone else to decide what concrete mix I'm going to warranty.

The engineer spec'd the concrete for the job. The GC ordered the trucks, and hired the crew, having inspected the site, and knowing the concrete specs. When I double checked with him on the 5-8%, he answered "That's standard for slabs so yeah, I priced it accordingly. ��"

This is the exact reason I had them order the concrete themselves

 

[joes169]

I can guarantee you that full air entrainment is NOT recommended for power troweled concrete.

Best of luck figuring this all out, but it sounds like you need to have a discussion with your GC first.

 

[g1teg]

I can guarantee you that full air entrainment is NOT recommended for power troweled concrete.

Best of luck figuring this all out, but it sounds like you need to have a discussion with your GC first.

Yeah I'm not arguing that, I never told them to power trowel either... That's why I hired an engineer to spec it, and a company to manage and pour it... This is all new to me!

I'm mostly looking for opinions on the best repair that will last, so I can be sure I don't get screwed in a few months when it separates or something... Thanks for the input for sure!

 

[ard]

Id hire one more pro:

a concrete construction (litigation) expert. So you know what to demand from the GC...



sorry to hear. I cant tell you how to remediate. Grind, polish, densify for a polished look? or grind then epoxy? 8" should be plenty thick. But that assumes it is only a surface defect and the bulk strength is unaffected

 

[ConCretin]

Sounds like you’ve already figured out the problem so I’ll just add my two cents. It appears to be a pretty clear case of de-lamination caused by steel troweling of air entrained concrete.

The chemical admixture that is used to achieve the air entrainment slows down the release of bleed water. If the surface is sealed too quickly with steel trowel blades, rising bleed water and air pool just below the surface creating a void and leaving the thin surface layer detached from the concrete below. Given the weather conditions and the fact that he had to add water to the surface during finishing, this is almost certainly the case.

Your finisher was apparently aware of the fact that the concrete was air entrained so he bears some culpability. He should have warned against it or taken steps to mitigate the potential problem. Given the specifics of your placement, there wasn't much he could have done however. De-lamination was almost inevitable in your case for the reasons you mention; weather, vapor barrier, depth of concrete, etc.

In addition, there was no reason for the engineer to spec air entrainment on an interior slab in the first place so he has some responsibility here too. Air entrainment is used to resist damage from freeze/thaw conditions caused by moisture in the concrete. Moisture that isn't really present in interior slabs. The vast majority of architects and engineers are aware of this hazard prohibit air entrained concrete on interior floor slabs.

The good news - if there is any- is that de-lamination is a surface defect and the underlying concrete is fine. Once it is resolved, it won't be a continuing issue. You could attempt spot repairs but it wouldn't be very attractive or durable. You could remove and fill the de-laminated areas and cover the floor with an epoxy. You could also grind off the entire surface and polish the surface. Another option would be to overlay the entire floor with new concrete, which it probably what I'd do.

In all these scenarios, you'll want to find and remove all the defective concrete. The best way to do this is to drag a chain over the surface and listen for a change in tone. Once you find the bad areas, chip off the surface until you find sound edges.

It's really too bad this happened. Unfortunately, your not the first person to experience this problem and it sounds like you did everything 'right'. For a material used by the Romans a couple thousand years ago, concrete still confounds us regularly.

 

[g1teg]

Thanks all!

For me, since it's already an 8" pad, I don't really want to go thicker. The problem areas run almost entirely throughout the pad, edges are the exception, so patches don't make sense.

Ideally, I'll have them grind maybe 1/2" off, and polish the aggregate. I like the look of it exposed, and I won't have to worry about a top layer coming detached later.

Any issues with that idea?