Cracked and sinking concrete floor
#11
In my garage I have a triangled 5X7 piece of concrete broken and sinking on one end. I can lift it with my engine hoist and a red head anchor bolt. What should I put in to get it back to level? Sand. How would I pack it effectively? I have no desire to get to far under to pack it. Wet concrete or mortar and  how do I know it will come out level once it cures. Any other suggestions. 
Thanks.
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#12
Rent a small grout pump.  Some types have enough power to jack up the slab. Flowable structural grout is the product.
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#13
That flowable grout is very strong and will certainly do the job.
But, if all you need is something to take up space after lifting the slab, you can probably get by with a less expensive method.
 Same idea, but google flowable fill.  Just soupy concrete.  You could not set bolts in it as it would surely just pull out, and if you had exposed edges of it you should protect it.  But if it is just needed to effectively fill a space, it will do the job.
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#14
You may also want to look at foam concrete leveling.

Not really a DIY project, but they have some pretty dense foams that they shoot out of setups similar to what they foam insulate with.
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#15
(05-03-2022, 07:02 AM)srv52761 Wrote: That flowable grout is very strong and will certainly do the job.
But, if all you need is something to take up space after lifting the slab, you can probably get by with a less expensive method.
 Same idea, but google flowable fill.  Just soupy concrete.  You could not set bolts in it as it would surely just pull out, and if you had exposed edges of it you should protect it.  But if it is just needed to effectively fill a space, it will do the job.

You can mix this type from the orange store "soupy"; as in pancake batter consistency with a small package of flow control (It's right beside it for $3.50) . Add water to a bucket and use a "mud" mixer while slowly adding the product. It sets fast, so don't mix the whole bag at once. If you stuck a pipe in a hole and poured into a funnel on top, it would definitely flow down the pipe. Perhaps you could use a dowel plunger to force it sideways 'til it appeared at an adjacent hole. Then repeat. This is assuming the slab was already held at the correct elevation. I would drill a few spots along the crack to lock them at the same height.
https://www.homedepot.com/p/Rapid-Set-55.../202188447
Sign at N.E. Vocational School Cabinetmaking Shop 1976, "Free knowledge given daily... Bring your own container"
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#16
I think in order to fix the problem, you will need to properly compact the sub-grade.  Any of the above fixes probably won't do that.  My guess, without being there and seeing it, is that your easiest solution will be to remove the concrete, properly prepare the sub-grade, and re-pour.
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#17
No rebar? Personally, I'd probably cut it clean and pull it out and see what's going on under there. Repair the grade, tamp new stone under it and e-pour the area. You could drill horizontally into it and set rebar into the holes. Like they do when building an addition and butting up a new foundation to the existing. So you get a mechanical attachment. Then re-pour. Mud or foam jacking may not fix it and it may be difficult to get it all flush.
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#18
My garage is 70+ years old and due to no gutters or visible drainage - the floor is cracked and uneven throughout. I've never had the money or ambition to fix it.
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#19
I am with Snipe Hunter, Remove,  compact and repour. If were in my shop I would cut it so it would be a straight edge and probably square it off.
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#20
(05-05-2022, 02:13 PM)lift mechanic Wrote: I am with Snipe Hunter, Remove,  compact and repour. If were in my shop I would cut it so it would be a straight edge and probably square it off.

I completely agree. Re-pouring vs. coring and pouring structural grout is about equal in material cost. Breaking up and removing the concrete and then mixing and placing 10 bags of concrete mix is more labor intensive but offers more predictable results. A grout pump would offer similarly predictable results but then renting, cleaning, and returning it would add to the labor side. B.T.W. the O.P. did ask what to pack it with before asking for other suggestions.
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