Floor grinding. This ok?

[Kaizen]

Prepping my 30x36 slab that was poured last fall. Using epoxy so I plan on grinding it. The one place that I have an issue is two hundred sq feet area where they ran short and had to wait for a truck. Temps dropped and it didn't set right. Will grinding take this down ok or should I be doing something else?

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[ard]

Prolly ask to move this to 'Flooring'...lots of epoxy guys there...

Question: is this stable or is that top friable and just keeps chipping off?

 

[Kaizen]

Stable below that layer. Not like it's lifting on its own. That area had a lot of freeze and thaw so that is when it came apart

 

[brownbagg]

te epoxy will fill those hole, just make sure you have no high areas

 

[ard]

I'll take a stab, based on other threads in the flooring forum...

You need to remove anything that is poorly adhered to the stable concrete below. If that top layer will crumble with light hammer blows, then it is not something I want under epoxy.

Once you have removed the non-structural layer, then apply a trowel on filler. There are epoxy fillers. While a liquid epoxy will fill in some defects, that is a large area. Hoping the epoxy will fill that is a bad idea- it WILL telegraph through.

I beleive you can grind after you have filled- this will create a nice planar surface- any trowel marks or defects will be ground off.

Primer the floor, with a specific 'pre-epoxy primer'. While you could skip this, and do two epoxy coats, the primer is far cheaper. It will control the penetration of the epoxy coat, giving more uniformity

Proceed with epoxy, flake, topcoat, whatever.

 

[Kaizen]

I'll take a stab, based on other threads in the flooring forum...

You need to remove anything that is poorly adhered to the stable concrete below. If that top layer will crumble with light hammer blows, then it is not something I want under epoxy.

Once you have removed the non-structural layer, then apply a trowel on filler. There are epoxy fillers. While a liquid epoxy will fill in some defects, that is a large area. Hoping the epoxy will fill that is a bad idea- it WILL telegraph through.

I beleive you can grind after you have filled- this will create a nice planar surface- any trowel marks or defects will be ground off.

Primer the floor, with a specific 'pre-epoxy primer'. While you could skip this, and do two epoxy coats, the primer is far cheaper. It will control the penetration of the epoxy coat, giving more uniformity

Proceed with epoxy, flake, topcoat, whatever.

Thanks ard. I'm going to try grinding it to a lower level then the rest of the floor. I think I can transition it as it's only an eighth low. I don't think it's stable enough for filler but if the grinder isn't taking it up I will put a skin coat of self leveler. Good news is that's my wood part of the shop so. I heavy traffic.
Ordered primer and epoxy with topcoat. Gonna be a project


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[Kaizen]

Ground it twice very slowly keeping the whole area level with no dips. Worked out well taking loose stuff off and smoothing the edges. With the several layers and flakes it won't be to bad

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[6768rogues]

If temperature drop did that, it must have really dropped down. Heat of hydration will let it go down to around 25 degrees without any freezing.
It looks to me like what happens when someone trowels water into the surface, either bleed water or added water. That dilutes the surface of the concrete and seriously affects its strength. Then it scales or spalls like yours.

 

[Kaizen]

If temperature drop did that, it must have really dropped down. Heat of hydration will let it go down to around 25 degrees without any freezing.
It looks to me like what happens when someone trowels water into the surface, either bleed water or added water. That dilutes the surface of the concrete and seriously affects its strength. Then it scales or spalls like yours.

I'm not a concrete pro. That section was poured like the rest of the slab and the only difference was the sun went down. It was in the 30s that night. They had been waiting for two hours when I sent them home at 9. It looked acceptable for the money I paid. Never planned on making it a fancy floor at that point so didn't care. The important parts are nice. That side will be covered by sawdust and cabinets


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[bigjon]

That floor is repairable. Hopefully Scotty, Shea, Justin or Armorpoxy reply. If you don't get it 100% a full flake floor will hide all the imperfections anyway.

 

[NitroShark]

I had similar a issue in some spots on my floor. After grind, I skimmed over with surface epoxy (same used for control joint filling) Then coated, - my floor was about 40mills DFT . Which is thicker than most people go.


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[Kaizen]

I had similar a issue in some spots on my floor. After grind, I skimmed over with surface epoxy (same used for control joint filling) Then coated, - my floor was about 40mills DFT . Which is thicker than most people go.





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I'm using silkaflex in a caulking tube on my control joints. Do you remember the name of what you used? Can it be applied thick?


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[NitroShark]

I used Tnemec surfacing 215 epoxy. Totally different than what you're going to try.

 

[Kaizen]

I used Tnemec surfacing 215 epoxy. Totally different than what you're going to try.

i'm not going to put silkaflex on this just in the control joints. thanks for the info