Shotcrete applied to the inside of an inflated fabric form

Method used e.g. for the construction of thin-shell domes where construction starts as a concrete ring foundation, reinforced with steel rebar. For smaller domes, an integrated floor and ring foundation may be used. Vertical steel bars embedded in the ring beam footing are later attached to the steel reinforcing of the dome itself.
The fabric form, fabricated to a proper shape and size, is attached to the concrete base. Using fans, the form is inflated - creating the shape of the dome. The fabric form is both the form for construction of the dome and the outer roof membrane of the shell when it is finished. The inflator fans run throughout the construction of the dome shell.
Approximately three inches of polyurethane foam insulation is applied to the interior surface of the Airform.
Steel reinforcing bars, or rebar, is attached to the foam using special "hooks" embedded in the foam. The rebar is placed in a specially engineered layout of hoop (horizontal) and vertical steel rebar.
Shotcrete, a special spray mix of concrete, is sprayed onto the interior surface of the polyurethane foam, embedding the rebar. After three inches of shotcrete is applied, the dome is a steel reinforced, concrete structure.