Rastra is a registered tradename for a particular

insulating concrete form Insulating concrete form or insulated concrete form (ICF) is a system of formwork for reinforced concrete usually made with a rigid thermal insulation that stays in place as a permanent interior and exterior substrate for walls, floors, and roofs. ...

(ICF) construction system, Rastra created the name Insulating COMPOUND Concrete Form (ICCF), used to make walls for buildings. It is one of the earliest such products, first patented in 1965 in Austria. Rastra is in production since 1972, and is composed of

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...

and Thastyron. Thastyron is a mixture of plastic foam and cementitious binder that is composed of eighty-five percent recycled post consumer

polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a ...

waste that is molded into blocks and panels.

Production

Rastra is

sustainable Specific definitions of sustainability are difficult to agree on and have varied in the literature and over time. The concept of sustainability can be used to guide decisions at the global, national, and individual levels (e.g. sustainable livin ...

in its production because no energy is used in the curing process, and only one to three

kilowatt hour A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bil ...

(kWh) are required to make each >10sqft block. After the blocks are trimmed to exact size, the remaining debris is recycled to create new blocks. No byproducts are released in the production process that are considered a burden to the environment.Rastra Insulated Compound Concrete Form System (ICCF) Construction Building Blocks For Houses & Commercial Buildings
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Building

Rastra blocks come in different sizes, and can be easily cut with woodworking tools to form the desired shape. These blocks are commonly attached together with clamps or glue to form a grid-like system inside.

Rebar Rebar (short for reinforcing bar), known when massed as reinforcing steel or reinforcement steel, is a steel bar used as a Tension (physics), tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concr ...

is then run through the grid, which is then filled with concrete.

History

Polystyrene concrete was invented in 1960.

BASF BASF Societas Europaea, SE () is a German multinational corporation, multinational chemical company and the List of largest chemical producers, largest chemical producer in the world. Its headquarters is located in Ludwigshafen, Germany. The ...

, a German chemical conglomerate, originally created this product, but found no successful applications. An Austrian-Swiss-based company modified the product and created what is known as Rastra.

Fire rating

As a thermal barrier, Rastra has a four-hour fire rating with no flame spread and no smoke development. A five-hour fire endurance test of a ten-inch-thick wall with temperatures exceeding two thousand degrees Fahrenheit on the face of the wall showed that the wall did not conduct heat. This lowers the risk of health hazards during a fire and also makes building repairs easier afterwards.

Physical properties

Thastyron has a

compressive In continuum mechanics, stress is a physical quantity. It is a quantity that describes the magnitude of forces that cause deformation. Stress is defined as ''force per unit area''. When an object is pulled apart by a force it will cause elon ...

strength of 56

pound-force per square inch The pound per square inch or, more accurately, pound-force per square inch (symbol: lbf/in2; abbreviation: psi) is a unit of pressure or of stress based on avoirdupois units. It is the pressure resulting from a force of one pound-force applied to ...

(psi) and a

tensile strength Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials t ...

of 43 psi. Rastra has a low toxicity level. Rastra is highly frost, fungus, and mildew-resistant. The sound insulation is greater than 50

decibel The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a po ...

(dB).

Insulation

As a heat insulation, Rastra keeps a room at a constant temperature and evens out temperature changes, both of which can lower energy use. It also has a low heat penetration depth, meaning the wall surface keeps a constant temperature.

References

{{Reflist Building materials Concrete