Suggestions for preparing ground for concrete.

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henhen59

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I am going to install porcelain tile on what on what was supposed to be a concrete floor. After removing the old tile what I was left with is a parcial concrete floor, areas of dirt from where chucks of concrete was removed and what seems like clay (moist dirt in the kitchen).

The guy who is going to fix the floor said he was going to remove the "loose chunks" of concrete and pour new concrete to fill in the "holes". At first I was thinking he was talking about bags of "ready-mix' concrete, just add water, and produces a soft pasty pourable concrete...but then he said he his going to mix up cement, rocks and sand. I am worried about what has to be done to the present disaster of a floor to prepare it for concrete pouring and what size aggregate should be added to the cement and sand (being that the concrete floor that is there now is about 2-3 inches thick).

Any suggestions on 1) Preparing the ground/floor for pouring and 2) anything particular about aggregate size. Any info will be appreciated so I would know where I stand. I have seen and read huge amounts of info on the internet but where I am now, things seem to be done as if it was 100 years ago.

Attached are two pics.
floor1.PNG
kitchen floor2.PNG
 

highup

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I can't tell but what's there looks pretty thin. If some of it crumbled out down to bare dirt I'm betting the rest of it is pretty darn weak.
I'd be buying a used or cheap skill saw with a blade that can cut concrete, then renting a jackhammer.
I don't know what it actually looks like in person but from the picture that looks pretty bad.
Personally, wouldn't let, some guy, fill in the places where concrete is missing.
I see doing nothing less than hiring an actual concrete company to come take a look at this and give you their professional opinion.
You already know that something does not feel right that's why you came here. Get a good concrete finisher to come look at that.
 

Jon

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From here it looks like you would only need a spade
What did the existing floor look like before you attacked it?
All broken up or kinda "solid/attached" ?
 

MikeAntonetti

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I’ve seen every possible way of tile down and it’s insane how well bonded I’ve run into. If a bomb was dropped on some tile floors it would act as shrapnel and still have Thinset on the slab. Doing a Thinset removal Wednesday where the guy picked up tile under a floating lvp. So there absolutely will be a new method of tile install where it’s not attached to slab.
 

C.J.

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There is already floating tile on the market. It’s set in a plastic grid that snaps together then gets grouted. QuicTile, Snap Stone… You can even order some from Amazon.
 

MikeAntonetti

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There’s been some attempts but long term performance I’m not sure.

what I see as fact that when tile is bonded so well to slab the cracks in slab move, the tile is not flexible so they crack like twigs.

the sheet membrane to prevent cracks is a mess trying to remove.

there’s aesthetic reasons for change out, color etc. which is also a heavy cost.
 
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C.J.

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Prolly bout the same as any other floating floor. Most people either move or get tired of what their looking at before too long anyway.
 

highup

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To the original poster.
We love to hear what your project turns out like when it's completed.
 

SCFLOORSYSTEM

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I am going to install porcelain tile on what on what was supposed to be a concrete floor. After removing the old tile what I was left with is a parcial concrete floor, areas of dirt from where chucks of concrete was removed and what seems like clay (moist dirt in the kitchen).

The guy who is going to fix the floor said he was going to remove the "loose chunks" of concrete and pour new concrete to fill in the "holes". At first I was thinking he was talking about bags of "ready-mix' concrete, just add water, and produces a soft pasty pourable concrete...but then he said he his going to mix up cement, rocks and sand. I am worried about what has to be done to the present disaster of a floor to prepare it for concrete pouring and what size aggregate should be added to the cement and sand (being that the concrete floor that is there now is about 2-3 inches thick).

Any suggestions on 1) Preparing the ground/floor for pouring and 2) anything particular about aggregate size. Any info will be appreciated so I would know where I stand. I have seen and read huge amounts of info on the internet but where I am now, things seem to be done as if it was 100 years ago.

Attached are two pics.View attachment 12263View attachment 12264
The first step you will need to do is either scarifying the existing concrete or to use a primer made for new concrete or self leveling use the specific primer. The primer will allow the new concrete to bond existing concrete. If this is done correctly the additional topping (cement) will be “joined” together. Either way of these will or should get done, if not you could have settling issues and movement to wind up with hollow spots are “voids” between the two.. this installer may mean a “bed” which is wire lathe sand, Cement and aggravate.
Best of wishes your project goes as plan!
 

zannej

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Wow. Looks sort of like a semi-outdoor bathroom. Too bad it's not possible to epoxy over the rocks and have some sort of rustic-looking rock floor. Some people like that stuff.

But in all seriousness, that looks like a mess. They need to dig down several inches. Will probably need some sort of metal mesh support and then pour concrete in. If he doesn't bring a whole truck, he better have a mixer going and a ton of bags of concrete. Problem is, I think it takes something like 30 days for it to cure properly before it is set up sturdy. I could be wrong though. It will likely get pretty warm in that room while it cures.
 

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