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I watched a special on Discovery the other night about future houses. They showed a beautiful round house built from this product called RASTRA. This product could easily be molded and carved into a dome structure. I snipped a few things from different web sites.

Offered by Leila.

RASTRA's beneficial qualities include:
4 hour fire rating
High insulation value
No toxic outgassing
Energy saving
Sound attenuation
Pest resistant
Seismic 4 System
ICBO ER-4203

What is RASTRA? RASTRA is a concrete form system made of a lightweight material Thastyron which provides a permanent formwork for a grid of reinforced concrete to form load-bearing walls, shear walls, stem walls, lintels, retaining walls, and other components of a building. Thastyron offers the ultimate in properties for a wall, such as insulation, soundproofing, fire protection, all in one easy-to-install element. Thastyron also is resistant against frost and heat radiation. It does not entertain mold or attract nesting insects. And 85% of its volume is recycled material - postconsumer polystyrene waste - which very likely would have ended up in landfills never to disappear.

Concrete filled into the cavities of the elements provides excellent strength. The channels inside the elements have been designed to provide optimum strength while using the lowest possible amount of concrete. The square grid allows use of the elements either vertically or horizontally maintaining the grid and the runways for reinforcement. By using different strengths of concrete and various amounts of reinforcement, the load capacity can be adapted to any requirement.

A primary building product is RASTRA, an above and below grade wall system that breathes like a house made of natural materials yet has superior earthquake and wind resistance, pest resistance, noise reduction and acoustics, a 4 hour class A fire rating, and an insulation value that exceeds code in most States. RASTRA is an insulating concrete form (ICF) made of recycled expanded polystyrene (EPS) bonded with cement and non-toxic or low-toxic additives. Basement walls and Stem Walls can be built in less than half the time it takes to form, reinforce, brace, pour, strip, and insulate a conventional concrete block wall. A RASTRA exterior wall can be quickly finished with a single coat of stucco - no mesh or lathing is required.

We need the engineering properties of RASTRA compared to concrete. What is the tensile, bending, shear strength? What is the density? What is the comparable cost? By the way does any one know what Seismic 4 System ICBO ER-4203 means?

Offered by Mike.

Hi Mike,
Saw your name on the zetatalk. Strength data for Rastra are on Rastra web page Seismic 4 system refers to possible design for seismic loads in seismic 4 areas, like CA. The ER 4203 is the evaluation report number. For more info contact Rastra.
Karl Holik