Concrete
Concrete building in marine environment has a long tradition that goes back to ancient rome.
In modern times floating concrete shell structures has been used for industrial purpose on a large scale in the oil and gas industry.
The advantage of floating concrete shell structures over steel is the by far better maintenance free service life of the structures that is estimated in some 200 years.
Many spectacular concrete shell structures like TROLL A - in use for over 30 years in marine environment are in excellent shape, and perform outstanding.
There has been experiments to use concrete shell building in shipbuilding. Although concrete ships performed well, a concrete ship will not fit well into the existing (steel oriented) ship support infrastructure so concrete as a building material has been limited to special segments.
Industry platforms is one of them, submarine applications and seasteading will be others.
