Help Filling a void under garage floor

[Rod N]

Hello Gents,
I need some advice on filling a void under my garage floor.
Had a 2 post lift installed and when drilling found a 1" void then solid concrete again. Floor is about 12" thick, void about 3" down.
My plan is to open the floor beside the foot of the lift and then fill the void from the side.
I've seen products like poly level, but can't find a place to buy it.

****, maybe, but rather not have issues down the road with the lift.

Any advice out there?

 

[kbs2244]

I would call a "mud jacking" co.
They can drill a fill hole and a relief hole and then pump in the concrete.
It will spread out to fill the void completely.
It may take a lot of concrete.
If you have settling in one spot you may have it in many.

 

[rlitman]

If you have settling in one spot you may have it in many.

Settling would be a void UNDER the concrete. He's talking about a void INSIDE the concrete, though a 12" pour sounds pretty thick to me.

How big is this "bubble" cavity? Can you probe around it with a wire?

 

[rsanter]

Are you sure? Could there be a sub slab, then foam insulation and then the top slab?

Don't know,,,,just talking

Bob

 

[fourjeepin]

12", wow.

 

[kbs2244]

Don't they make ultra-sonic scanners for this kind of question?

 

[boobag]

i highly doubt you have a 12" slab

it sounds like you have a 3 to 4 inch slab and either settlement below that or you have foam.

 

[chase237]

I would tend to agree that you don't have a 12" slab. What you might have is a previous repair for settling, i.e. mudjacked, that has continued to settle. If someone pumped mud underneath the slab I suppose it could separate from the slab and sink creating what would seem like a void.

Not sure how plausible that is but I have some settling in an area of my garage that had previously been mudjacked. I can tell because the patches are bad.
I just had it poly foam injected and while it's better it's not perfect. The only real fix is to tear it out and re-do it. $$$$

My 2 cents

 

[Rod N]

There is living are below, hence the 12" of concrete. The previous owner was a contracter and had heavy equipment in there. Major beams and posts in the basement.

You can tell there is a void there by knocking on the floor. Also when we drilled the bit dropped while drilling. I don't think there is any foam or sand in the void as nothing like that came up the hole.

 

[Diesel Dan]

Our shop floors are all of 12-14" thick with a basement underneath.
Interesting that there is such a hollow spot. Wonder if a two part epoxy patch material would work?

Edit:
Fill void with epoxy and use longer Hilti bolts that go into the lower part of the slab. That way the epoxy would be used for compression. After the hilti bolts are installed two smaller holes drilled, one on each side of bolts, to insert the epoxy and let air escape while injecting.

We use two part epoxy to patch surface blowouts and it has a high compression rating.

 

[Rod N]

Ya. I'm really starting to wonder if I don't need to break a tile and start busting concrete. Does anyone know have big of a hole they need to pump epoxy in?
Maybe a camera probe to snoop around?
I'm trying to get in touch with the 2nd last owner who did the install to see if he can tell me anything.

 

[boobag]

what supports the floor? do you have spancrete?

 

[Rod N]

what supports the floor? do you have spancrete?

Steel beams and posts underneath.

 

[Rod N]

What is spancrete?

 

[LifeLongWNYer]

Spancrete is pre-stressed concrete planks. When it is made, they run steel cable through the mixture, then stretch the cable. After the concrete is cured, the tension released and the cable is cut flush with the ends of the plank.

When you look at the ends of the planks, there are oval, sometimes round, passages through the plank. Great for running wire, plastic tubing for heat, etc.

A buddy of mine built a house with Spancrete and heats the basement and first floor floors with water heated by a solar panel. On hot ( brilliant sun shine ) days in the winter, he gets too much hot water, and gets rid of it by shunting it into his garage floor, which is also Spancrete.



JBP

 

[Diesel Dan]

Does anyone know have big of a hole they need to pump epoxy in?

You could always drill all you holes for the lift anchors and fill through those holes before you insert the bolts. The epoxy is pretty watery since it is self leveling.

Edit:
Forgot lift was already installed.
I think a few 1/2 or 3/4 " holes would be fine.

 

[Rod N]

You could always drill all you holes for the lift anchors and fill through those holes before you insert the bolts. The epoxy is pretty watery since it is self leveling.

Edit:
Forgot lift was already installed.
I think a few 1/2 or 3/4 " holes would be fine.

Can you buy the epoxy off the shelf?

I can only find companies that do it.

 

[Rod N]

Update.
I didn't mention that the last 2 anchors the installers went to drill holes for they said they hit metal 3" down and stopped drilling. Not rebar, a metal plate they said.
So yesterday I decided to see what was in the hole. No metal, just some 1/4 stone.
F###ing lift monkeys!!!
My 1/2" hammer drill with a 3/8" bit kept going.
They charged me $750 and baled without finishing.
Not sure if I should mention the lift company.
Anyway.
Advice on filling the void?
Can I do it myself or should I have it done professionally?
My guess is it will not be more than a gallon of epoxy.

 

[Diesel Dan]

Sorry I haven't been able to get you a product name yet.
They guys I've asked at work that use it don't recall the name of it, they aren't responsible for purchasing it. I'll ask around some more when I get back in a couple days.

Told them about your issue and they think it would work fine. It is so watery when mixed up it should have no problem filling all the voids.

 

[rlitman]

I'm not so sure epoxy is a good answer. Epoxy liberates a lot of heat while curing. A coffee cup full of the liquid will get too hot to handle. If you pour epoxy too thick, it can light itself on fire, but in the least, over a few inches thick, it will get hot enough to not cure correctly.

I'd use a self leveling (pourable) hydraulic cement/grout made specifically for pouring into thick sections. DryLok comes to mind, but that stuff sets FAST!

 

[Rod N]

I'm not so sure epoxy is a good answer. Epoxy liberates a lot of heat while curing. A coffee cup full of the liquid will get too hot to handle. If you pour epoxy too thick, it can light itself on fire, but in the least, over a few inches thick, it will get hot enough to not cure correctly.

I'd use a self leveling (pourable) hydraulic cement/grout made specifically for pouring into thick sections. DryLok comes to mind, but that stuff sets FAST!

I hear what you are saying.
I'm hoping not to have to pull a tile and use the 2 3/4" holes intended for the lift.
Therefore I need to be able to pour it into the hole. How fluid is the Drylok?
If it expanded as much as foam it would be perfect.

 

[Diesel Dan]

If I can get the name of the product one can call their tech line for advice anyway.

 

[Rod N]

If I can get the name of the product one can call their tech line for advice anyway.

Thanks Mr. Dan

 

[rlitman]

Therefore I need to be able to pour it into the hole. How fluid is the Drylok?
If it expanded as much as foam it would be perfect.

It can be mixed at different ratios to change the fluidity. You'd have to check the instructions, but the idea is that the more water you add, the weaker the final product. However, even severely watered down, it should be as strong as your concrete, and certainly stronger than the air it replaces.

But because it sets so fast, I'd do a practice run through a 3/4" hole drilled in wood.

It doesn't expand that much, but if it expanded like foam, it would crack your floor. This hardens to a cement like consistency.

You're looking for a flowable grout like this (though I don't know where this stuff is sold):
http://www.quikrete.com/ProductLines/NonShrinkPrecisionGrout.asp

Compressive Strength at 28 Days:

Plastic - 14000 psi (96.5 MPa)
Flowable - 12000 psi (86.5 MPa)
Fluid - 8000 psi (55.2 MPs)

Also, if you're pouring it into a hole through a funnel, you might want to stick a tube into the bottom to allow air to escape while you're filling it.

 

[Rod N]

Looking at all the options discussed here I think my biggest problem will be filling the void completely through the 3/4" hole.

 

[Diesel Dan]

Looking at all the options discussed here I think my biggest problem will be filling the void completely through the 3/4" hole.

For that reason I'd want something very fluid and none expanding.
No telling how large the void is. Realistically you won't get it 100% full but should get most of it filled. There will always be some air pockets, aka high spots, in the void you won't be able to get.

 

[Diesel Dan]

This sounds like the type of product we use at the shop.
Maybe give them a call.

armor-hard

 

[Rod N]

I only need to fill the void under the lift. A couple square feet. I'm starting to wonder if I should go back to plan 'A' and remove a tile beside the lift and feed it from the side.

 

[Rod N]

This sounds like the type of product we use at the shop.
Maybe give them a call.

armor-hard

Thanks again.

 

[wired]

Is your purpose to strengthen the area under your lift? or just take up void space? Polyurethane spray foam is an alternative. I know these are expanding products, hence find someone that can help you in your situation and has knowledge of how much to use, where to drill holes, ect, ect. Type this into the net, (lifting slabs with polyurethane) or (high density foam for concrete). Both products can be pumped into any void under a hard surface. Just an idea...

 

[Rod N]

Is your purpose to strengthen the area under your lift? or just take up void space? Polyurethane spray foam is an alternative. I know these are expanding products, hence find someone that can help you in your situation and has knowledge of how much to use, where to drill holes, ect, ect. Type this into the net, (lifting slabs with polyurethane) or (high density foam for concrete). Both products can be pumped into any void under a hard surface. Just an idea...

Yes it is just so the floor doesn't collapse the 1/2" where the void is.

I've watched lots of floor jacking on U-tube etc. My project is small in comparison the what the pros do.

I just need a can of the stuff! lol

 

[DC73]

Could you not just use some self-leveling concrete?

Like this: http://www.homedepot.com/p/Custom-B...-lb-Self-Leveling-Underlayment-LQ50/100192482

When I watch them pour this stuff on DIY shows, it seems very fluid and shouldn't have any problems flowing through a 3/4" opening.

DC

 

[BillK]

Rodn,

Although I am a die hard do-it-yourself type of person, if I was in your shoes I would be calling someone for advice before filling that void. Two things come to my mind. First of all, is there any possibility that what you are doing will somehow compromise the slab and cause a collapse ?? Probably pretty remote possibility but you just don't know. Secondly and probably more important is the fact that you are installing the lift on top of the void. That is a pretty critical attachment and I would not want to be taking a chance on it not being safe. Maybe your lift guys had the right idea when they bailed on you They might not want the responsibility of installing the lift on a unsafe slab.

I would get somebody from a concrete company to come and give you some advice before proceeding.

Just my opinion,

 

[wired]

Geo-Grout or uscomposites.com/foam.html the 16 lb density foam is claimed to be as hard as rock. Just need to find out from them on how to pump it in. Couple more products.

 

[Rod N]

Thanks for the info gents.
Upon further inspection I'm only seeing about a 1/8" void, which is good and not so good.
The good is talking with the owner of the lift company he is telling me worse case scenario the floor will crack and maybe settle in a spot. Nothing catastrophic.
Now the not so good. I really think I need to fill the void with a liquid. The floor leveling product is a great idea. (Thanks DC73) But at 1/8" how do I get it in there?
Small tube and a syringe?
It's great bouncing my ideas off you guys and hearing your suggestions.

BTW The lift guys bailed because they said the hit a metal plate. After using a smaller bit and then blowing out the dust, I found it was rebar. Very frustrating as they said their concrete bit would go through rebar. All my searching shows you need a special bit to go through rebar. I think they just wanted to go home.

 

[rlitman]

Under 3/8", I don't see any problems with epoxy. Have you looked at West System? You can get it in quarts and gallons. It's almost as thin as milk when no thickeners are added to the mix. Might be cheaper at a local marine supply store if you can avoid shipping costs...

 

[Rod N]

Wouldn't regular floor leveler be the easiest?

I'm in Canada and many of these products are not available here.

 

[DC73]

The floor leveling product is a great idea. (Thanks DC73) But at 1/8" how do I get it in there?

Just drill a larger hole down to the void with a masonry bit and a hammer/rotary type drill. The leveling compound will fill it back up for you.

DC

 

[Rod N]

Some pics

 

[Rod N]

Another