Lifting the corner of a walkway

Old 05-22-20, 12:40 PM
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Lifting the corner of a walkway

On a concrete front walk that's probably 30 years old, 1 panel has sunk a little (3/4" of an inch?) and water would pool there for a bunch of years now.

I (foolishly??) got the bug in me to fix it.

I dug under the low corner and Using a car jack (1 1/2 ton cap) I lifted it almost level with the panel next to it. (wasn't able to get higher than that - the jack was straining / really hard to pump it up more / afraid I might bend the lever on the jack.

I started realizing - even if I get it level / higher (to allow for settling).... then what? What do I do to keep the panel up / allow for settling. And there;s a gap now between the bottom of the concrete and undisturbed dirt... (yeah, it's just dirt under it? I thought there'd be an inch or 2 of gravel?)

Oh, and how to get the jack out THEN fill the area (taking the jack out = the corner will sink?

Any thoughts on the panel weighing more than 1 1/2 tons? Or is it likely binding against the next panel?

YES, I did look around a while ago for a company that does this work, but no one I found was interested in a small homeowner job like this.

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Old 05-23-20, 11:30 AM
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Did the corner break when you raised it? If not try to find some bricks or something to prop it up. Use something that won't rot. Take the jack out. If it stays up then force all the concrete you can under it. It would be nice if you could inject some grout under some pressure. I don't know just how to do that on a small scale. Maybe squirt some grout under with a grout bag to get it pushed further back. Make the mix pretty runny so it can flow under. Put something in front of it to block it from running where you don't want it to run. The more mud you get under it the better. With care you can vibrate the slab and even the mud itself and the ground around to get the grout to settle in and maybe add more.
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Old 05-24-20, 05:03 AM
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You've actually made your situation a bit more difficult. You've excavated a nice deep hole right where you need firm, undisturbed soil to support the slab. Now that' you've got the big hole I would work out some way to hold the slab in the correct position. Then fill the hole and any space underneath the slab with concrete. After the concrete has cured for a day or two then remove your temporary support.

For jobs like that I use a piece of equipment (loader or excavator) to grab the edge of the slab and lift it up. Then it's an easy matter to shovel some fine crushed stone, dirt or sand underneath to support the slab at the correct height.
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Old 05-24-20, 09:01 AM
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The jack is also sinking as you jack it. Soil does not have unlimited compressive strength, so you are probably reaching a point where the forces equalize. It does not mean the pad weighs 3000 lbs. About all you can do is drive a couple big long stakes down next to the pad, then force those stakes under the pad to help support it, and lower the jack. I agree that filling the hole with wet sloppy concrete is going to provide the best support.
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Old 05-24-20, 08:14 PM
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Thanks guys!

Pilot - so true - disturbed where I wanted firm soil : ) Now I realize that : )

I found a video where a guy used a C clamp and the jack on the ground.

I'm looking to do that - 1 end of the bar will be a cinderblock / other end is the jack.

Any thoughts on a C clamp being strong enough for this? a Harbor freight type of clamp? I didn't see any ratings on c clamps from there or elsewhere.

And I am a big proponent of 'with the right tools you can do anything : ) '.

Most times though, I don't have the right tools : )


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