Does anyone have experience with homes built from Grancrete "ceramic concrete" sprayed onto styrofoam?  As a geopolymer, Grancrete is functionally similar to shotcrete and gunnite, but it is a phosphate-based magnesium-oxide about twice as strong as Portland cement. 

It is sprayed on both the exterior and interior of a styrofoam form.  The compressive strength is rated up to 12 kpsi, and it has embedded glass fibers that help resist cracking.
 
It is a very quick-drying alternative to shotcrete, and it does not absorb moisture.  This is not Portland Cement.  Brown Homes in Idaho builds stucco style homes using grancrete:

http://www.brownhomes.org/Grancrete/Grancrete.htm

United States Patent 7402542:

http://www.freepatentsonline.com/7402542.html

Argone Laboratory originally developed this concrete product for the DOE to encapsulate spent nuclear fuel. It is very strong, fire-proof, crack-resistant, non-absorbant, and acid resistant:

http://www.anl.gov/Media_Center/Explorer/Fall_2004/honor_newmaterial.html

It makes a really nice looking stucco style home as well as countertops, showers, tubs, swimming pools, etc. and it is more reliable than concrete:

http://www.brownhomes.org/Brochures/Brochures_Photos.htm

Grancrete is classified a geopolymer and also goes by the name "ceramicrete".  I'll be experimenting with this product to repair damaged concrete flooring in the battery plant where I work.  I'm a project engineer.

This Company uses GFRC, but Grancrete can be substituted.

Wonder if anyone has used it for flat roof applications for the waterproof low expansion strength factor

if you want to know about Styrofoam i will refer you with this link Styrofoam concrete forms, i hope this will help you.