Lifting a cement floor

[Andamo]

My two story 3 stall 24 X 36 garage is 11 years old and has a cement floor. I normally park in the center stall. The last 2 years, and especially this past winter, I've noticed the water that drips off my car after the snow melts, runs away from the drain in the center of the floor and puddles in a low spot. The other day I was moving some things around in the far corner of the garage, and I can see where the cement has settled in a 15' x 10' area. It's moved down about 3/4 to 1'' with the actual corner looking to be the lowest. All my roof drains and 2 of the roof drains from the house all exit underground in this corner. Has anyone ever had one of those companies come in a drill holes in the concrete and pump something down into the holes and lift the concrete back up ? I know I need to find out if it's the water that is causing this to happen, or is it just settling for some other reason. Oh yeah, the ground isn't level and slopes downhill. The right short side had only 2 blocks laid, but I think there are 6-7 blocks on the left short side.

 

[motofly196]

Yes, there are companies out there that lift concrete that settles. When I was stationed at Travis Air Force Base, CA, we contracted a company to lift several concrete slabs on our airfield that had settled out of spec for our aircraft. They did an analysis of the concrete (cracked, spalled, base course pumped away) and core drilled in several areas, followed by pumping in a foam material (that looked just like "Great Stuff") I talked with the Project lead alot about how they did it, and he said that he did residential projects as well. They operated out of Utah, but serviced the West Coast. It sure saved us alot of man hours! Our other option was removing the slabs (20'x20' and 24" thick...with dowels installed in 2 sides). After seeing it done, I would definately recommend it, as long as your concrete doesn't seemed cracked.
For the 3 years I was stationed afterwards, it never settled again...and we received ALOT of rain in that time frame!

Scott

 

[Cavalier]

I used to do this work known as Slabjacking, Mudjacking, or Pressure Grouting for a number of years. Settlement of all types of concrete slabs is common, and can happen to a garage floor poured within a foundation.

They dig deep to pour the foundation, then when it cures, they pull the forms and backfill without compacting the ground, and then pour the slab on top of the loose fill. Over time the fill under the slab begins to settle and the heavy slab (floor) sinks down on top of it. Since you have drains running underneath the slab, you need to have them checked to see if they are leaking, as water can erode away at the ground under the slab.

The process is basically done by pumping a cement grout through 2" holes strategically placed in the slab which will fill the void under the slab then compact the ground to the point where the slab has no where to go but up. This process works with great success, and is usually less than half the cost of replacement. You can walk on it immediately, and park on it the next day. An area 10x15 down an inch or two should be able to be done in a couple of hours.

I am sure you can find a contractor in your area to do this work. Here is a web site with good info on this type of work:

www.americanconcreteraising.com

Good Luck

 

[Andamo]

Actually the water from the downspouts from the garage and house go around the outside perimeter of the garage. The only piping under the slab is from 1 floor drain that doesn't seem much water. I dug out some pictures of garage while it was being built and found out the entire area was filled since the ground had a slope to it. They put pea gravel in overtop of the fill and ran a Bobcat inside for many hours over 2 days. So the bottom line is, I think because of the area I'm in ( north of Pittsburg ) and see the freeze thaw cycle, the fill just settled and the slab followed. I have a call into a company to see about lifting it back up. I guess it'll depend on the cost of repairing it to see if I'll do anything about it.