A specially shaped slab of concrete is laid flat on the ground, on top of a vinyl air-bag, which is then inflated. Within a few hours the concrete forms a stable shell.
A team from the university has made a test dome measuring approximately 18 by 11 metres wide, and three metres high.
A curved shell is very strong and saves on materials, said Benjamin Kromoser, from the Institute for Structural Engineering at the TU. The inspiration for the shape comes from nature – such as snail or nut shells.
Currently building large concrete domes requires support structures made of wood – which makes the process very expensive and requires longer construction times, Kromoser said.
The segments of the concrete slab are attached to metal rails that ensure the slab is inflated evenly. The inflation of the test dome – with a wall thickness of five cm – took only two hours.
If the dome is cut it can become a bridge. Photo: TU Wien
Johann Kollegger, from the TU, compares the design of the concrete slab to an orange peel, which has been cut in a spiral and then spread flat on a table. "But we do it the other way round, we start on the flat and then construct the curved shell."
The scientists have already patented their technique, and hope to be able to produce more complex, free form shapes in the future. At present the maximum span of the dome is 50 metres.