After the rigid foam insulation, the radiant heat, the plastic vapor barrier and lots more reinforcing rebar was in place, it's time to pour the slab insulation. Since the slab will be the floor in this house, it needs to be more or less perfectly level. To achieve that result, we hired a subcontractor who deals with this everyday. They arrived with a team of eight or so, many of them related through blood and marriage I gathered from the conversation. Kevin and I were there to direct and supervise. The sub brought a huge concrete pump truck with a big boom to shoot concrete. It was a perfect day to pour - on the colder side with solid cloud cover but no rain - so the concrete could be leveled and manipulated for a good hour or so before it was too hard to move.
Two guys manned the boom, while another two did the initial pass of getting the liquid concrete level, and two more followed to get the level precisely with big "bull floats" that skim across the surface of. Another one stood around; I'm still unclear on his role. It was lots of action and lots of noise for about four hours, then they packed up and left, and we were left with an impressive slab of concrete slowing curing and changing color.