Canadiangeek.net How do you know you can't do something if you haven't tried

Yesterday I pulled both my van and my truck into the garage to ensure that the mounting points were close enough to the car yet far enough away that the doors could still allow me to climb in and out. I might have got a little carried away and decided to see if the weight of my 6000 lb truck would be ok... I lifted the truck 2" off the ground and the concrete gave way. Pulled the rear anchors right out of the slab. (that's why i only raised it 2 inches, truck didn't have far to fall.)

So now to fixing the problem. I used a side grinder (big one) with a masonry blade and cut out a square that is 3" wider then the lift plate in all directions. The blade is round so i cant get all the way into the corners without making a mess. I then went to the hardware store and bought a 10lb sledge hammer and started to beat the crap out of the square. Unsurprisingly it came out pretty easy. This did leave a substantial amount of dust on everything in the garage, i put plastic over the engine so no concrete dust would enter the intake/exhaust ports.

Now that the holes are done you can see what happened. The builder started by putting Re-bar directly onto the ground (not elevated at all). It would appear that the re-bar sunk into the soil a little before a 2" concrete slab was poured. The re-bar was sunk into the ground so the concrete never touched it (it floats under the floor). Many years pass and the ground started to sink leaving the re-bar just below the slab and creating a void.

You can see all of the cracks in the slab in the photos... now i know why.

The thickest point is 2"... most of the slab is thinner...

So the plan is to first call a slab jacking company to come look, I would like them to pump their liquid concrete under the complete slab. I think it would be best to put the 6000PSI footings in first, then have them drill a series of 1" holes around the slab to pump in their mixture.

In other news I finished off the last of the brake assemblies now the the parts have arrived. I was side tracked with the concrete work but i should have the column done today or tomorrow.