I'm in the process of repouring my garage floor. It wasnt properly backfilled when it was installed in 1970.
Here's a pic of it right when I bought the house:
Here's a pic after the old stuff was removed:
The top of the concrete slab started at the bottom of the first course of bricks. There was an air gap of 12-14" around the edges. Luckliy they had it tied into the block with some rebar.
My original plan was to rent a plate compactor and run it over the dirt. Then bring in a triaxle of the crushed limestone and backfill/compact it up to grade.
The ground is still really soft though. I can pound my prybar (3/4" diameter solid) down 4 feet with a sledge hammer in only 5-6 swings. I only weigh 155 lbs too so its not because I'm Mr. muscle. Thats in the center of the floor too. Its even easier at the edges.
What should I do? Do I need to worry about compacting all of it? I'm planning on rebaring the crap out of the new slab as well as installing some PEX tubing for radiant heat.
House is in Erie, PA so there is freeze/thaw.
There is a full basement on the house.