Concrete raising /jacking? question

[SJorgensen]

Hi Guys,
My little shop is in a one car garage. One of the pieces of concrete slab is about 1" lower than the adjacent piece and it is lower than the next. When it rains I can get two inches of water in my precious little work shop. The drainage isn't too bad because it dissapates quickly (probably with a little more soil going with it.) The structure is over 50 yrs old so the damage isn't quick. I now have electric service there but for a long time I was using cords. In a different year I might have just build a new shop, but since the Bush administration took over, I don't think I can afford it. My question is about "jacking" concrete. I was wondering if I drilled some 3/4" holes and pumped some sand/water slurry into them, could I level out the concrete. All ideas are welcome (except for Democrat bashing!)
Thanks to all,

Spence

[SGW]

Hmmm...interesting idea. No idea if it would work.

If you could "somehow" pump in the slurry under pressure, it seems as though it might. But I doubt there is any way to know, for sure, except by trying it.

You're probably aware that concrete is very strong in compression, quite weak in tension, so lifting by prying is liable to crack something. Lifting it hydraulically seems like a really good approach...if you can get it to work.

[lynnl]

I d'unno Spence, you may need to consult with Hillary or Dick Gebhart or Tom Daischle about this one. Just kidding. (Democrats have mama's and daddy's too, Ya'know!) ...tho they're parents are probably dumocrats as well! Actually, so far as political affiliation goes, I feel very strongly both ways. They're all A**H*les! They're the ruling class and our pockets are ripe for the picking! I just happen to like the Republicans' line better.
But, back to your question: I haven't a clue. ..sorry, forget I spoke.

Humor aside, I'm likewise interested in the suggestions forthcoming.

[SJorgensen]

I don't want to get this off track, because I really do want some on-point advise. I wonder if the news and political topics shouldn't be in the "networking" or some other section. I know someone has dealt with "concrete jacking." I do appreciate all of the input, even political, and especially international political input. I hope that Alister can tell me how the Scottish jack a piece of concrete (if they ever do.) That land is so old and stable over there. (hah!)
Spence

[shoprat]

yea its dne all the time around here by a couple of different companies.i am not sure how it compares in pice to replacing it i am sure it is cheaper i used to do a lot f concrete work a few years ago and i thing mud -jacking is a somewhat temporary fix because there was a reason your slab settled and it will do so again i am afraid .

[SJorgensen]

Shop Rat,
Is that another term for this? "Mud Jacking"?
I know some people are familiar with this.
Spence

[Thrud]

Spence
You could have some serious problems there. The first thing you should do is see if you are losing soil under slab. If this is the case a civil engineeer should be brought in to assess the situation as it could be a major problem.

We had a mall up here that had a concrete slab sink in their parking lot slightly - right up to the point a 30' sinkhole opened up and swallowed several parked cars in the area.

If the structure is very old, it is probably just settling from improper footings over time. It might be easier to apply concrete patch over it to level the pad. I have seen asphalt mix used to do this too.

You could dig the pad up and repour it. If you do make sure the soil is compacted well and has proper sized fill for drainage for your soil conditions. This might be less work compared to trying to level the old pad.

[CCWKen]

That's done a lot on side walks here in South Texas. I don't know if it will work on a slab. There's much more weight in a slab and that means more pressure will be needed. I guess if the "void" under the slab was large (area), you would get more lift.

Our ground down here seems to shift after heavy rains and/or dry spells. (Read: all the time) There are many contractors down here that use the dig, jack and post method on homes and garages but probably because they can charge more.

[Rich Carlstedt]

Don't know if this will work for you, but it did for me 25 years ago.
lived in a small town (Canada) and no jacking services available. My 12 foot wide concrete driveway sunk 3 inches in front of the garage door just after I moved in.
I borrowed two "railroad" Jacks.
They are very heavy and sort of work like auto bumper jacks.
Dug a hole on both sides of the section (10x12) ,set the jacks in so they could lift the section on the low end.Trenched out each side of the slab so i could see the rock base
By alternating carefully with the jacks,I raised the section 3 inchs higher than I needed (looked like a ski jump going into the garage).
Shoveled fine beach sand under the slab, and put a garden hose under the slab (middle) and more sand. Pushed it in with a hoe until I felt that I was a good 1" higher than needed. back off the jacks and sure enough, I was about one inch high.
Turned on the water hose, until the trenches on each side started to fill up with water, and jumped up and down to settle the slab.
my wife drove the car on it while i watched.
The cab weight and me hitting a 4 X12 wood block with the sledge gradully dropped it down to where I wanted it.
Shut off the water while pulling the hose out.
Would help if it didn't have the brass end on it , Or you could just cut it off.
Didn't drive on it for 2 days.
it was solid.. never moved in the 4 years that I lived there after....and it only took about 4 hours max time

[SJorgensen]

My pursuit of the problem has lead me to some interesting information. I was in a conversation with some elderly neighbors that were on their way to church. (Not the direction that I was going!) I asked one neighbor if he remembered what was on my property before my 4-plex was. It was as though a light bulb had gone off in my, 90 year old neighbors, brain. I hear a story that, as yet, I haven't found any documents to support. But here it is. There was a house here. The owner of the house was a bad-ass biker. The house was a nuisance because of the biker gang in the early 70's. The owner went to Alaska on a fishing trip. His wife had an infant baby. There was a fire. The wife escaped the fire. She reentered the fire to rescue the baby. She rescued the baby but after a week the baby died of smoke inhalation. Shortly after the mother died of burns, smoke inhalation, or maybe a broken heart. I had no idea of this history, but it is an interesting history and I have spent many hours in my shop reflecting on it. And on the physical aspects I have to think of what is happening to the property. I would like to hear from anyone that isn't creeped out about this. There is probably a floor drain in the old structure that is exhausting the soil that was compacted above the old artifacts. No bad vibes around here, but I still don't have proper drainage. I would like to change the topography enough to get the concrete in my shop above the high-water-mark. Any ideas on concrete jacking are appreciated.
Thanks to all,
Spence

[darryl]

I don't know the size or thickness of your slabs, but if they're not too thick, you could rent a concrete cutter and cut a criss cross pattern in the slabs, then lift each smaller piece individually, pack a crush mix down and settle the piece. Once they're all at level, fill gaps with sand. It sounds like you will need the drainage ability anyway. Find out first if there is rebar in the concrete, by using a metal detector, or a powerful magnet hanging from a string. If this is an option for you, then you might raise all the concrete enough to get around the water problem.

[Ian B]

Spence,

Have a look at

http://www.concretenetwork.com/concr...ab_jacking.htm

and

http://www.concreteslabjacking.com/

Seems this is what you're thinking of. If you go the DIY route, the next problem's going to be how to pump cement slurry (probably need a reciprocating pump), and what pressures you'll need.

Not sure how large / thick your slab is - could you help it by grouting eye bolts in and lifting with chain blocks, then pour a cement slurry in through holes? May be easier than the hydraulic route if the slab's not too heavy.

Good luck,

Ian

[Alistair Hosie]

Spence the answer to this would be a little easier to give if we knew exactly where the water you talk about is coming from you don't say however.The problem is as far as I can see it is (question) should you jack up the slabs and pour in concrete in order to level the floor. I would say definitely no to this as this seems a bit like sweeping the dust under the rug eventually it may come back to haunt you.It is obvious you are simply guessing at what can be causing your concrete slabs to subside and there is no point pouring in concrete only to find out afterwards that you will eventually need to dig the whole thing up.I would be very tempted to lift a slab or two(or perhaps they are too big for this I don't know) and see what is going on underneath.You well may be over loose earth but then there could be an underground spring or just insufficient footing. So in my opinion don't close your eyes to the potential future problems which could arrise from pouring in thinly mixed concrete as a quick fix method.In my opinion ( for what it is worth) it is better to bite the bullet and get it put right now and then you will sleep well at night, and have only time in the future to think about enjoying your shop instead of every time it rains worrying about damp and eventual rust problems which could occur as a rersult.
When you do fix it you must get the base above the soil level which surrounds the building and, we here in UK put down (when building from new) a membrane of poly vinyl which covers the whole floor before re concreting over it this will help avoid rising damp.Sorry I could not offer more encouraging advice but I would hate to see you come to grief with this in the end. kind regards Alistair

[Paul Gauthier]

I must be missing something but I can't understand why you would go through all that work of lifting concrete slabs.!!!!!!!
Clean you slab with muriatic acid, rinse thouroughly, and pour a new slab over it. Problem solved, floor is flat, in two days move your equipment back in.

------------------
Paul G.

[Alistair Hosie]

Paul.
Yes you could do that it would resolve the issue with unevenness. but you would still need to know why the slabs are sinking and where the water is coming from.If it is coming from beneath the slabs it would need to be investigated especially if it is flooding the shop with two inches of water.I for one would like to resolve this before doing what you suggest which if the water problem did not exist then would be ideal Alistair