When will be available for general use the products in Roman Concrete mix? Just with use of Volcanic Ash as arid, the resulting Concrete résiste under Sea water for millennia. The Windsor building fire in Madrid proved concrete pillarse withstood temperatures above 1'000° C for a long time. If you find a mix with no water and air porosity, with a solide tightness, you could even thinking in making something as an Space Shuttle in Concrete. Karlsruhe tech built a kart on a pre-stressed concrete plate, with a body thickness of four millimeters. Blessings +