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Is it possible to use a hydraulic bottle jack or similar to rotate a 10 x 12' x 6" a few degrees or about 5 inches?

I have a recent pour not quite in position.

3/8" rebar throughout in a 6 x 6 grid formation (6 pieces at 9ft, 6 pieces at 11ft, 6" actual thickness + 1" tamped gravel.

UPDATE

ROTATED APROX 12" WITH NO PROBLEM 20-ton bottle jack laying flat against 4x4 steel tubing buried in the ground 3ft. Damn naysayers!!!

@isherwood Thank you, sir.

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    If you paid someone to do this, make them remove and do it over correctly. If this was DIY and you don't want to remove it, then it depends on whether you can live with the error, e.g. by filling a gore with more concrete. – Carl Witthoft Jan 22 at 19:52
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    Go look at a few concrete pads close to this size and see how many have cracks without being moved, if it is still green less than a month since poured just trying to lift it will probably crack it. – Ed Beal Jan 22 at 22:04
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    Shoot us a picture and we might be able to toss out some better ideas, like: doing nothing because it's something only you notice, or downsizing the structure to fit. – Mazura Jan 25 at 1:22
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A healthy 6" slab is probably robust enough to handle quite a bit of movement without cracking. You just need to lever it around, not lift it. (Maybe that's what you meant.)

  • Clear all material away from the slab in the direction it's to be moved.
  • Pothole at several locations on the "push" side of two corners about 12", tight to the slab.
  • Insert a 6-foot 2x4 in each pothole, and stand it up with the narrow edge against the slab. Place a block between the lever and the slab to prevent damage to the slab edge.
  • Block against the bottom of the lever.
  • With helpers, pry the levers in the direction of movement.

Depending on the nature of the substrate, the slab should spin with relatively little effort. (Ideally it was poured on gravel or washed rock.) Once it's in the new position, check level. Then...

  • Using a garden hose, jet under the slab at approximately 24" intervals from opposing sides, just enough to get the hose to the center. This will soften the soil and allow re-settling. Avoid jetting crosswise near the ends so you don't remove too much soil there.
  • If the slab needs further leveling, jet in more frequently at the high side and flush out a bit of material.

Finally, return to the levers and give the slab a few nudges to encourage a final settling action. Let the soil alone for a few hours to a few days so it can desaturate and stabilize before applying weight or movement to it.

Warning: If you get clever and start winching on these levers, use your head. A heavy stick of lumber becomes a loaded weapon when stressed. A slipped tether or broken strap can knock out teeth or much, much worse. This much weight brings inherent risks that must be respected.

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    This is just terrible advice. I have had issues moving a concrete pad for an airconditioner and getting it to sit flat after. Also you shouldn't be resting the concrete in soil - it should be a small rock/pebble aggregate. Spraying this and thinking that the concrete will wiggle into place is foolish. Spending this much time, energy and money to do this is crazy. Concrete pads can be moved but the limits are very small slabs and often they aren't worth the time. – DMoore Jan 22 at 20:50
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    Thanks for your thoughts, Ed, but I've spent many sweaty hours demolishing 6" slabs, and they are strong--dramatically stronger than a 4" slab. You could just about span the 10 feet with one. Anyway, this is what I'd do, and I'd have high confidence in the outcome. Your mileage may vary. – isherwood Jan 22 at 22:00
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    +1. Either you and I are the only ones who've ever actually moved slabs around, or everyone else uses totally crappy cement. - Not 2x4s though; you want 4~6 big ass guys with railroad bars. It weighs like 3~4 tons, but you don't have to pick it up.... just give me a place to stand. - "This assumes a mature slab (14 days plus with plenty of moisture)." – Mazura Jan 23 at 3:12
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    Given this particular slab is on tamped gravel, I am inclined to think it would rotate without deformation, as the gravel would tend to conform more readily to the ground below than it would the concrete above. (That is, the gravel is the most liquid-like surface in this sandwich.) – bishop Jan 23 at 4:08
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    This can definitely be done, the pad weighs about 5 tons so you'll need a powerful jack and a strong fulcrum to jack against – Jasen Jan 23 at 7:01
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Slab on grade is probably the kind of pour you are referring to.

The problem is only partially one of lifting the slab, the other half is having the slab rest again on the grade.

These kinds of concrete pours fill all the irregularities of the ground they are poured upon. If one could lift the slab without slab damage, the setting of the slab on a new position of the grade would likely not match the irregularities in the same exact positions. This means your slab would be unsupported in some spots, and have new pressure points in others.

While one would hope that the weight of the slab pushes down the high points. In reality, the weight of the slab does so by bending at the high points while applying pressure. Since typical formulations of concrete aren't designed to be heavily flexible, the bending introduces fractures and causes premature failure of the slab.

I would look into augmenting the existing slab without attempting to move it.

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    This is the answer. The bottom of a large concrete slab poured into rock/soil looks like the bottom of the ocean - not flat. No way this thing goes back into place flat without some major voids. – DMoore Jan 22 at 20:46
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    A slab moved slightly tends to carry some of its substrate with it, leaving virtually no voids (and likely none that won't span just fine with a 6" beast of a slab). We're talking a few inches and the sky will not fall. This assumes a mature slab (14 days plus with plenty of moisture). – isherwood Jan 22 at 22:02
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You might get some inspiration from some attempts at various slab moving jobs posted to YouTube. It's more translation than rotation in place but you can get a sense for how strong a slab is.

  • Moving a Patio Slab -- fabricates a bolted down steel fixture pressed with a bottle jack, demonstrates the slab displaces. Sheers off a 1/2" 5/8" bolt, upgrades to 3/4" bolt. Zooms in on slab, you can see it actually move each pump of the jack. 10'x15' slab
  • Moving a Concrete Slab -- a smaller slab, uses a pry bar to lift one edge, slips in bricks, uses a floor jack to lift, slides in some roller logs to move the slab. Approximately 3'x4' slab
  • Moving a concrete slab -- Approximately 5'x6' slab moved using steel pry bars, something like 5" metal pipes as rollers, and a piece of plywood to roll onto.

Definitely out of reach but this so called slab crab attachment to a digger shows how robust a slab can be Slab Crab moving Concrete Slabs - Kenco

Not quite related, but a great company service where folks lift sunken slabs with hydraulic jack and drills holes into the slab to inject some expanding foam Lifting Sunken Concrete Driveway Pads

I believe if you get the geometry right so the forces are oriented properly you should be able to make a configuration of those steel fixtures and bottle jacks to push at the right places to achieve a rotation. It may also be possible to push in one place and pull in another with like a snatch block pulley arrangement with a come along or something.

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    Great post. The first video inspired me with some small modification... worked great!! – Merkd yesterday
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If it doesn’t crack or break up while moving it it probably will later because the bottom side is never perfectly flat. Concrete is very brittle and has no shear strength that’s why we add rebar and wire mesh, even if you have reinforcements I would not try to move it.

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    A 6" slab that's not carrying vehicles would probably survive if precautions are taken. Most sidewalks, by comparison, are only 4". – isherwood Jan 22 at 20:28
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I'm not sure how feasible this is but, here's an idea: you might want to look around for a 'mudjacking' service. Here's a video isn't great but should be enough to understand the process.

This kind of service is typically used to level concrete but perhaps the approach could be used to float the slab. Then the slab could be rotated by other means.

If the entire slab can be floated in this way, it would address the issue of uneven support that is described in other answers. If this is even possible, it might raise the entire slab a bit which may present other issues.

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This is just a guess.

I don't think there's going to be any muscling this around or moving it with prybars or etc. It's going to weigh 9000 pounds or so. Realistically I don't think it's going to happen.

But anything's possible, of course. I tried to think of some ways this might be doable. Most of them were way more work than busting up the slab and starting over. One might actually work.

If you put nine 3/8" expansion anchors in the slab, in a 3x3 pattern, put eye bolts in them, and rigged chain sling to a big shackle, set up so they're all under equal tension, and picked it up by the shackle, maybe with an excavator, you could probably get it up off the dirt, spin it, hose down the dirt under it, and lower it.

So yeah probably best to learn to like the angle, or crack it up.

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    You might be right, but the sliding friction of a 9000 lb. thing on dirt is much less than 9000 lbs. Obviously it depends on the substrate and the flatness of the slab bottom, but I think it's worth a try. – isherwood Jan 23 at 19:54
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I once moved an 8x12 slab (~4 inches) about 20 ft and 90 degrees from the original pour. Builder put a shed up when we built the house. It was 10+ years old when I moved it. Dug two holes under one edge and put bottle jacks. Surprisingly, the slab did not break when lifted clear of the soil - no stones just poured on the dirt so yeah the bottom was uneven (and I would doubt there was any rebar or wire in it). When I moved it I put it on a bed of sand hoping that would be soft enough to be stable. It worked for well enough for a tool shed. I took the structure (in tact) off the slab before moving. Lots of one foot 3" dia pvc pieces for rollers on boards worked for the shed and then the slab. BTW if you make a large airbag out of duct tape and plastic sheet or tarps and inflate it with a leaf blower you can lift the slab off the supports so you can rearrange them. I did this move by myself, so it took a while. Probably should have paid to have the old one broken up and poured a new one properly - but just so you know it can be done.

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