On some roof decks, light-weight insulating concretes are used as fills or toppings. They are poured over another sur- face. They might be poured over something like corrugated metal or form boards. The con-cretes are made of lightweight insulating aggregates mixed with Portland cement and water. The insulating concrete is mixed, pumped in place and leveled at a job site.
Cellular concrete is another insulating concrete.
This concrete has small air cells in it. Gypsum Concrete Roof Decks Gypsum concrete roof decks are made of gypsum material mixed with fillers. The mix-ture is called a slurry. It is poured over form boards that are supported by framing. The concrete mixture has steel wire mesh in it to make it stronger.