<http://schema.org/about>
"We have never been fond of concrete for single family residential uses; there is too much gravel excavation, carbon released making cement, transport of a heavy, marginally recyclable material to house a couple of people. Yet there is something to be"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/green-architecture/gigacrete-an-alternative-to-concrete.html>