The benefit of using insulating concrete during building construction is that it keeps the heat outside in the summer and inside in the winter. Insulating concrete does this much better than standard concrete.

Concrete does not have a very good insulating value, and neither does steel. The mixture of the two will add structural stability to what you are building, but it (commonly) will not enhance the concrete's insulating value.

The carpet and pad are insulating you from the concrete floor.

Poured concrete has an R value of about 0.08/inch. Fiberglass batt has an R value of about 3.14/inch (blown fiberglass wall insulation is about 3.2/inch). From these values we can calculate that the equivalent insulating thickness of concrete would be about 3.5x3.14/0.08 = 137.4 inches.

Note that concrete blocks have a somewhat better insulating value due to the incorporated air pockets.

A 4" concrete block has an R value of about 0.2/inch

An 8" concrete block has an R value of about 0.15/inch

A 12" concrete block has an R value of about 0.1/inch

This term may be referring to a carpenter who "forms" concrete. That is setting forms to place concrete into for walls, floors, footings and such.