A woman asked me to come to her house and give her an estimate on some work she needs done. Well, I wasn't prepared for what I saw. Apparently, she had her garage floor torn out and re-poured recently, but by 2 different companies, at two different times, of course. One half turned out really nicely, the other was a disaster.

The half that failed seemed to have bubbled for some reason. There was a big broken hump in the middle of the floor, exposing the dirt underneath. The dirt looked loose , and I saw no hint of re-bar of any kind.

She wants it fixed, and made to blend with the other half of the garage. I'll gladly do the work, but need to clarify a few things first.
1) shouldn't the dirt underneath be tamped down first?
2) shouldn't re-bar be installed before the pour?
3) when is gravel used as an "under-layment" instead of dirt?
Thanks for whatever insight you can provide!
G.P.R.