Lost in bigger news at the end of December was this story from World Science Net about "spray-on" buildings. Grancrete, a sprayable ceramic which hardens quickly into a solid form, is...
...stronger than concrete, is fire resistant and withstands both tropical and below-freezing temperatures, the developers said; it keeps homes in arid regions cool, and those in frigid regions warm.
To build a home, Grancrete is sprayed onto Styrofoam walls, to which it adheres and dries, according to the developers. The Styrofoam remains in place as an effective insulator, although Wagh suggests simpler walls, such as woven fiber mats, also would work well and further reduce the raw materials required.
Grancrete is made from local materials, including sand or sandy soil, ash, magnesium oxide and postassium phosphate, found in fertilizer. It's still in testing, however, particularly for earthquake and hurricane resistance. The developer, Dr. Arun Wagh (at Argonne National Laboratory), is originally from India, and hopes to see Grancrete used as an inexpensive and quick building material for the poor. Grancrete was a 2004 winner of R&D Magazine's top 100 innovations. More details and a photos of a Grancrete building in production are available in this PDF from Argonne National Lab.
This would appear to be an easy plastering material for strawbale homes.
A similar product, DryVit, was recently taken off the market because of moisture infiltration problems. I hope that this proves to be a better technology since it really is a good idea.
I had the same question about moisture problems. In a conversation with Jim Paul, the co-developer of grancrete, I was told that grancrete thermochemically bonds to the styrofoam, so that moisture infiltration between the two materials is not be possible. The bond is stronger than the styrofoam's bond to itself. If this product is for real, I believe it will have an impact on the construction industry even greater than SIPs or ICFs.