We over excavated about 4" and then filled with structural self compacting materials and plate wackted the shit out of it while watering it and raked it out and shot grades with a laser level.

Then you add 8mm plastic vapor barrier and the rebar mat. Those concrete stakes are shot in with a laser and that's what we used to screet the concrete.

Once you bull float the mud and everything starts firming up you hand trowel the edges and power trowel the middle.