The RASTRA® Building System is the only stay in place insulated concrete form system (ICF) of its kind. RASTRA® is a sustainable, energy efficient, environmentally correct construction system. RASTRA® is produced out of recycled, post consumer plastics - such as expanded polystyrene, which is mixed with cement. RASTRA® offers the structural strength of concrete paired with high thermal insulation, sound attenuation and fire resistance. A truly "green" building material for houses and commercial buildings.