The beams are being incased thickly in concrete ( below floor level) to act as transfer slabs, the floor itself will be much thinner and higher, you can see the vertical form work. These transfer slabs will support the interior core walls.
That Slab looks like it's going to be more then a foot thick, it is going to give off a CRAZY amount of heat as it cures,, we aren't talking about a 5 inch slab and -20 here.