Dome prototype #1 was hand plastered, without vibration, leaving some small concrete voids. One inch of closed-cell urethane foam was sprayed onto the interior. #1 is now installed as a playhouse in Juneau, Alaska. Winter views after two years.
Dome prototype #2 was sprayed, using the same concrete recipe as for #1. After cure, forms set was removed, ready for re-use, and the concrete dome was static tested by loading it with 545 kg of sandbags. Then, it was buried in a sandpile with 1 m of sand on top, causing < 0.25 mm deformation. In another video -- vimeo.com/158664023 -- we see the seismic testing of #2. Neither static nor seismic testing caused visible damage to #2. These scale model, proof-of-concept, concrete domes are ~ 1 cm thick. The ideal size for human use and for this construction method is probably ~ 6 m equatorial diameter, 5 / 8 sphere volume, with shell thickness ~ 2 cm. Primary reinforcement is tiled and overlapped "C-Grid" by Chomarat.
Bill Leighty wleighty@earthlink.net
