Well I built a concrete dome. The concrete was 70% by weight of various levels of crushed lava rock out of the side of the hill in Kona, the cement was made on Oahu, and the fly ash came out of the powerplant on Oahu.
I have several concepts I'd like to try next that use larger lava rocks in a stacked wall with mortar and a reinforced backing. Also a type of roof that uses super thin layer of concrete, in a hypar shape (hyperbolic parabaloid). I was considering then covering this roof with natural thatch, either grass based (pili, if I can find enough) or coconut palm (Mexican looking). Yeah the thatch would be very flammable, but the roof under it wouldn't burn.
One of the worst challenges on permitting is insulation requirement. Requiring insulation means you need to build in a hollow cavity somewhere for you to stick the insulation, or use foam board. Speaking from experience, a concrete structure in Hawaii does not need insulation. The thermal mass of it releases so much heat at night that it takes most of the next day for it to start coming through, by which time the sun is going down again.
I have several concepts I'd like to try next that use larger lava rocks in a stacked wall with mortar and a reinforced backing. Also a type of roof that uses super thin layer of concrete, in a hypar shape (hyperbolic parabaloid). I was considering then covering this roof with natural thatch, either grass based (pili, if I can find enough) or coconut palm (Mexican looking). Yeah the thatch would be very flammable, but the roof under it wouldn't burn.
One of the worst challenges on permitting is insulation requirement. Requiring insulation means you need to build in a hollow cavity somewhere for you to stick the insulation, or use foam board. Speaking from experience, a concrete structure in Hawaii does not need insulation. The thermal mass of it releases so much heat at night that it takes most of the next day for it to start coming through, by which time the sun is going down again.