[myfeethurt]

Hello everyone, long time listener, first time caller....
I have a large garage slab which has voids underneath that must be filled. I've confirmed by drilling 1" holes every 3 feet and checking the underside. Cavities average an inch or so in depth. I can run a water hose into a number of holes with no spray back.
I'm not looking to jack up the slab, I simply want to fill the voids BEFORE any serious cracking or slab displacement happens.
My local slabjacker is not answering the phone(out of business?)
I've concocted my own little device to pump a grout/slurry mix under there. It shouldn't take much pressure, besides, high pressure would risk heaving the slab. I don't want to order Flowable Fill from a cement yard, it will be too much for me to deal with. I'd prefer to mix up a 5 gallon bucket of a slurry/grout (non sanded) which I can pump in myself, as needed, as my time allows.
My cement experience is limited, the science blows my mind franky....
My question: What kind of Flowable Fill can I make on my own that will work? It doesn't have to be structurally strong, only as strong as packed dirt. Cement yard would'nt stop laughing when I asked them to deliver me a yard of Flyash. I don't know what else to use. What's easily available?
1 part portland cement, 20 parts???. Thank you in advance.

 

[bytor]

Perhaps bags of pre-mixed (just add water) non-shrink grout?
This type of product should be available at building supply locations.

 

[hdavis]

This is one of the few cases I'd suggest mud. I'm assuming this is not sitting on expansive soil.

Using a cement product, you'll be spending all your time mixing and clean up.

 

[Mike-B]

NS Grout
Rent a grout pump
Buy a bucket mortar mixer

Prep everything. Setup a few buckets with mortar in them, ready to go. Get you water measured out. Have your holes drilled. The bucket mortar mixer work quick as schitt.

Let her rip!

Sent from my SM-G970U using Tapatalk

 

[myfeethurt]

This is one of the few cases I'd suggest mud. I'm assuming this is not sitting on expansive soil.

Using a cement product, you'll be spending all your time mixing and clean up.

MUD is a great idea! Call me stupid, and others have, but where can I find pure mud, that has no rock, sand, chips, etc in it? Can you buy bags of pure dry mud somewhere? ADD 5% portland cement and I'd be in business.

 

[myfeethurt]

NS Grout
Rent a grout pump
Buy a bucket mortar mixer

Prep everything. Setup a few buckets with mortar in them, ready to go. Get you water measured out. Have your holes drilled. The bucket mortar mixer work quick as schitt.

Let her rip!

Sent from my SM-G970U using Tapatalk

Thank you Mike, I like your style...I can't find anywhere to rent me a grout pump(small manual AIRplaco type), only the huge line types at $500 a day, that are waaaaay overkill for my purposes. I only need 10 PSI at best, a 1000PSI line pump will blow this big slab sky high.
So I made my own home made manual pump that works just dandy.
Test went perfect using only portland cement and water. Flowed like
water and dried without shrinkage.
I just don't like using so much portland cement. AND the strength is
overkill. flyash 20 to 1 cement would
be excellent, but I can't get anyone to deliver fly ash.
Pure mud would be great if I could find that.
I'm afraid NS off the shelf grout won't have the needed viscosity.
I'm most likely gonna call my local CalPortland Tues and have them deliver me a yard of Flowable Fill (fly ash mixed with some slow setting portland cement). At a 9 or 10" slump.
I'll have 7 garbage cans ready for them to fill.
If it's under $500 I'll do it. IF I have extra, client says I can pour it into
her ravine and cover, which is what road crews do.
Thanks for your help and suggestions. Much appreciated.

 

[hdavis]

Don't be surprised if you order a short batch, and you find out it doesn't have the retarder in it when it sets up in the middle of working it.

 

[myfeethurt]

Don't be surprised if you order a short batch, and you find out it doesn't have the retarder in it when it sets up in the middle of working it.

Ha! Sadly, I wouldn't be surprised.
But, that's why we pay them the big bucks, because
we expect quality and service. Right?........crickets....

 

[hdavis]

I think you're begging for problems. Anything at all goes wrong and you'll have a mess. If you had experience and reliable equipment it would make a difference.

If it isn't flowing like you want, are you prepared to remix in the can with more water?

Once those cabs are filled, you aren't moving them. You're going to be taking a lot of steps to get it done.

 

[myfeethurt]

I think you're begging for problems. Anything at all goes wrong and you'll have a mess. If you had experience and reliable equipment it would make a difference.

If it isn't flowing like you want, are you prepared to remix in the can with more water?

Once those cabs are filled, you aren't moving them. You're going to be taking a lot of steps to get it done.

I get that, totally. AND I appreciate you amplifying that voice in back of my head. I figure I have about 2 - 3 hours before I can't
pump it, then I'd be dumping the rest. That's assuming everything goes
right. .....But now it's beside the point. Dispatch says they can't make me a mix of flyash/cement only, their specialty Flowable Fills all contain sand, so that takes care of that. I can't pump sand. Sooooooo, I will be mixing water with Portland cement only, and calling it good. It'll slow me down a bit, but it will be done right with no waste. It works, it's just
not what I wanted to use, it dries much harder than necessary. I wanted to try a ash/cement mix for the experience. Oh well, screw it.
I've already got 20 bags of Portland cement loaded in the van. Thanks again for your input. I'm a newbie posting here, I appreciate everyone for chiming in. Thank you.:clap:

 

[hdavis]

MUD is a great idea! Call me stupid, and others have, but where can I find pure mud, that has no rock, sand, chips, etc in it? Can you buy bags of pure dry mud somewhere? ADD 5% portland cement and I'd be in business.

I didn't catch this question.

You'd make this in a wheel barrow as a thin mud, and the big stuff settles out. For you, I think not being able to handle pumping any sand makes it a non-starter. Even loam usually has sand in it.

 

[18th Engr. Vet.]

What about getting pure dirt with no organics in it from a nursery and making soil cement to pump in? It would be very cheap, and it shouldn't take a lot of portland cement. Highways use soil cement as the subgrade, but they mix it really dry and compact it. Here in Tennessee, we get almost pure clay from around the river. It's usually only $20.00 per scoop, which is about a yard.

 

[EricBrancard]

You have any spray foam guys in your area that do foam slab jacking?

 

[18th Engr. Vet.]

I think I responded to the wrong person on this earlier: If you have a nursery around you, they might have soil with no organics, and around here in Tennessee we can get it for $20.00 per scoop of approximately a yard. We get almost pure clay, but I'm close to the Mississippi river. That would be the cheapest and probably the most flowable soil cement for what you need to do. I plan on doing the same under my porch slab, but I won't do a slurry, because I can get to it from the side and pack it in.

 

[18th Engr. Vet.]

For his situation with the small amount of fill he needs, I would be concerned that if he didn't drill larger holes in a checkerboard, then too much pressure might build under the slab and cause problems if using foam, but I haven't done any foam myself, and only seen it used for lifting (jacking).

 

[myfeethurt]

You have any spray foam guys in your area that do foam slab jacking?

yes, there are foam guys here, but I'm not interested in that.
That would be my last choice.

 

[myfeethurt]

I think I responded to the wrong person on this earlier: If you have a nursery around you, they might have soil with no organics, and around here in Tennessee we can get it for $20.00 per scoop of approximately a yard. We get almost pure clay, but I'm close to the Mississippi river. That would be the cheapest and probably the most flowable soil cement for what you need to do. I plan on doing the same under my porch slab, but I won't do a slurry, because I can get to it from the side and pack it in.

I had a small similar job a few years back. It had side access. I simply packed dirt in with a 2x4/sledge. Then a little backfill.
..............This job, is done. I finished by hand pumping portland cement/water only. Took me 15 bags, about 1/2 yard I figure. Big slab, 40 by 32, lots of cavities. Just glad it got supported before the footings
collapsed. 6 hours, with a helper mixing. Lots of time spent investigating.

 

[hdavis]

I had a small similar job a few years back. It had side access. I simply packed dirt in with a 2x4/sledge. Then a little backfill.
..............This job, is done. I finished by hand pumping portland cement/water only. Took me 15 bags, about 1/2 yard I figure. Big slab, 40 by 32, lots of cavities. Just glad it got supported before the footings
collapsed. 6 hours, with a helper mixing. Lots of time spent investigating.

Then cheaper and less risk than a short load.:thumbsup:

 

[18th Engr. Vet.]

Very cool. Did you make a pump out of threaded rod and schedule 40 pipe? With a drill, that makes a good pusher.

 

[sunkist]

Sorry guys I have read this thread a couple of different times and have yet to read what I think maybe a real solution for filling voids under this slab.

Having said that do I have a easy or cheap solution for the problem answer NO, because that's what all this is about how to solve this cheap I know how to solve it the real way but not the cheap way or Quick way.