Eight-five percent of a RASTRA® building block is composed of recycled post-consumer polystyrene waste. RASTRA® is a concrete form system that is made of a lightweight material called THASTYRON™. THASTYRON™ provides a permanent framework for a reinforced concrete grid that forms components of a building (load-bearing walls, etc.). By filling the cavities of the elements with concrete excellent strength results. The channels inside the elements have been designed for optimum strength while using the lowest possible amount of concrete. RASTRA® affords very good wall properties, such as insulation, soundproofing, fire protection, frost resistant and heat radiation. It does not entertain mold or attract nesting insects.

The production of RASTRA® elements can be classified as ecologically clean. No particles or fumes are set free during its production, and only a minimum of energy is required. The production of ten square feet of material consumes only about 1 KWH of electricity, and no heating process is involved. All residues of the production process are immediately recycled into another batch and converted into new RASTRA® elements. In addition, remnants from the building site can be shipped back to the plant and recycled.