OT: slab jacking with grout.

I want to raise a 14'x14'x4" floating shed slab 2" on one side. Slab jackers near me seem to want $750/hr. There do not seem to be any DIY resources for such.

I have this friend who makes sausage suffers out of 6" PVC pipe. He uses a simple oring sealed plastic piston, and city water pressure like a "water over meat accumulator" 40psi water pressure extrudes the ground meat nicely.

I read most grout pumping equipment runs 75-200 psi. It does not seem to be rocket science, I read all this about the process.
SLABJACKING

I can boost my water pressure over grout accumulator with a pump.
I already have the pipe (a scrap 6" 16 gage steel pipe), the piston material, and the appropriate pump. (pressure washer)
I think I can accomplish this for <$100 in parts so being a cheap ass I am considering trying to do it myself.

water over grout there is no tube explosion risk etc...

Any similar experience?

"Any similar experience?"

No, but I really like the way you think............Bob

How quickly do you have to work with the grout? You'd need a fairly good volume injected fairly quickly, without too much delay that would allow the setting up of the cement to commence. Is the grout going to stay under there while you do a retraction stroke with your cylinder, or will pressure have to be maintained continuously until the grout sets enough not to flow?

How do you control which part of the slab lifts to create the tilt (regardless of how the injection is made)?

My advice:

Try a small scale experiment first using a miniature version of your grout pump on something like a 24" x 24" x 2" paver. That will let you identify problems with only a small scale mess instead of a big one. I suspect lifting one side of a slab by pumping grout is not as simple as it might seem. Better to have an "Oh shit" moment on something smaller, cheaper, and lighter than that shed slab.

Many of my "great ideas" failed spectacularly on the first try and in several cases experimenting first would have resulted in less time and trouble in the long run.

Something lese not mentioned - what's under the slab to cause it to sink in the first place? .......slab jacking may well work, but for how long?

Have you got a heavy machine on that part of the slab?

Has the slab broken it's back or is the whole shebang out of level.

Is there any rebar etc in the existing slab? ......if not jacking may crack it.

14 x 14 x 4'' is less than 2 1/2 cuyds of concrete?

How quickly.... well, I'm not sure, but it can be chemically retarded. You're not shooting for making quality concrete, just something that doesn't wash out. They use mostly sand with a little cement and maybe fly ash if you want it very flowable.

As for it flowing out the holes, I don't THINK it's an issue. I've not seen any special care taken. The grout weighs about as much as the slab so its kind of neutrally buoyant. They (professionals) can move around hole to hole without trouble over the course of a lift. I might have a expanding rubber plug on hand just in case.

The instruction paper says use stiffer grout to raise it, and watery grout to fill voids.

Supposedly, if you need to come back after it sets you drill through the new grout and pump it up again.

In my case a groundhog undermined one side and the whole slab settled to one side. The hog has been gone for a few years. I might fill up to near but not to the underside of the slab with a very wet mix first, let it dry then jack it up. That seems counter to the instructions though.

My neighbor had 6 slabs of his driveway done a month ago. I had told the contractor to do my shed while he was there and had the equipment out. My shed is not 40 feet away, and I figured one more slab not a big deal. I would have paid him whatever the extra fraction of the total job. (He was using my driveway and my yard for access to my neighbors driveway even) He was, I think a jerk. He packed up all of his shit and did not do my slab. Then he quoted me $350 to come back and "try", $750 if he could "do" it for my 1 slab. He was talking about all the cleanup time on his equipment etc... and that pissed me off because he was already there and we could have avoided that cost.

Talking to the guy I know it's not rocket science, or even grade school science.

From what I understand about the process your biggest problem is likely to be keeping the pump hopper supplied with material.

Tough about the ground hog causing the problem. Many people have no idea how destructive burrowing animals can be.

I watched a building repair show this was on TV.


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All I can say is they did a nice job fixing that horrible dip in the road down the hill from your house. And they did it in about 2 days.

As a kid, the slab jackers at home had steady work fixing every farmer's leaning grain bins. It sure seemed to work well.

I've got some areas near my building's foundation walls that have been eroded by insects, I've had the idea of making a hollow auger to "lock into" the ground and then pump something like grout in as a preventive fix. I've seen no sign of settling, but I figure it's better to act beforehand.

Good luck on your efforts, keep us posted.

Homeowners insurance?

It may be covered under that...call to ask.

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Then he quoted me $350 to come back and "try", $750 if he could "do" it for my 1 slab. He was talking about all the cleanup time on his equipment etc... and that pissed me off because he was already there and we could have avoided that cost.

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If your fix works perhaps you can send before and after photos, and remind him you were ready to pay him to do it.

It could be however that he had other reasons to not do yours that day, or, it could be that he really was a jerk.

The calculation isn't what his time is worth, it's what your time is worth. If it takes you a day to build and test, and a day to do it, is your time worth about $40/hr? If it isn't, then go for it -- but know that if it takes longer to build, test, or do, you'll be pushing minimum wage fairly soon.

I find on projects like construction and repair, if I elect to do some myself I shoot for replacing the most expensive guy, so I get where you're coming from. But when I do electric work, or certain car or electronic repair, I don't have to tool up and invent stuff to do it. I just grab what I need from the tool bin and have at it.

Chip

Sometimes there is lasting value in doing it when someone else says you can't.

"No consumer repairable components within", oh how I hate the attitude expressed by that!

Google

You'll note the resemblance to a standard boating "bilge pump".....

We own a concrete leveling company and have been lifting concrete since 1988. Our machine shop exists to make and repair all of the related equipment.

Pumps are very simple, depending on resources and equipment you already have access to. For example, an old hydraulic cylinder and a billiard ball (check valve) could easily be made into a grout pump.

Grout materials vary depending on where you are in the country.
It does not need to “set up”. Look up mudjacking…many areas inject ground clay.

A manually operated pump is doable and less complicated, but will require some sweat equity.

A shed slab should move rather easily.

dsergison said:

...He was using my driveway and my yard for access to my neighbors driveway even.... Then he quoted me $350 to come back and "try", $750 if he could "do" it for my 1 slab. He was talking about all the cleanup time on his equipment etc... and that pissed me off because he was already there and we could have avoided that cost.

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Since the prior agreement was that he would use your driveway to stage the neighbor's job and then do yours, he broke the agreement.

Not sure you want to trust him again, but if you do, a bill for his prior use of your driveway could be a negotiating point.

Neil

partsproduction said:

Sometimes there is lasting value in doing it when someone else says you can't.

"No consumer repairable components within", oh how I hate the attitude expressed by that!

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I always read that as "Open me first".

Techno Metal Post and Helical Piles

JS said:

I watched a building repair show this was on TV.


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Cheers!

Tony

instead of jacking the slab...I did an entire in ground pool deck concrete with sinking such as yours with SPEED CRETE...cheaper...came in 5 gallon buckets...but only mix a small amount at one time...it hardens in 10 minutes...they use it on railroad crossings...holds 7000 lbs....water proof...that way it doesn't sink more from disturbing the underneath...my 2c...I used a dry wall blade...and you can sand it afterwards for smooth...maybe something you could look into...one bucket is only 80 bucks...you can drive on it in minutes...plus you make thick and it can go on ceilings

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