In the 1960s the first successful attempt was made to use low air pressure to lift and shape in a single operation all of the concrete and steel needed for a 300,000-cubic-foot dome large enough to contain an entire gymnasium. Refinements since then result in the construction steps shown.
- An inner membrane form made of a material such as nylon reinforced neoprene is laid in place on the foundation slab and attached to an anchorage eyelet.
- Steel reinforcement spirals are stretched over the membrane between anchoring rings on the perimeter. Conventional steel reinforcing bars are slid into the extensible reinforcement spirals.
- Concrete is placed and distributed over the reinforcement. Then an external PVC form is placed on top of the freshly cast concrete.
- Vibration equipment is positioned and inflation of the whole assembly begins. As the structure slowly lifts and takes shape, the spirals stretch and the rebars slide within them to their final positions.
- The external PVC form is removed and internal air pressure released only after adequate concrete strength has been attained.