Markets: Stone-Sandwich load-bearing walls

Thin CarbonFibreStone (CFS) sandwiching a thicker insulation in-between. Right Kolja Kuse(September 2009) CarbonFibreStone or CFS is a new technology, which could revolutionize building: using stone, not in massive blocks (see the August edition of, but rather in thin waffle-like elements. The elements are carbon fibre coated. This makes them hard yet flexible. Not only are they able to withstand heavy loads, they are remarkably resilient to lateral forces.

The German based company TechnoCarbon Technologies used the material to develop composite waffles or sandwiches. A 2.70 m-high CFS-element – the height of a normal building story and 1 m wide has been tested in cooperation with the Chur Technical and Business University in Switzerland to withstand a 20 t load – the mass of 3 stories.

The unique property of these building elements is that the stone element is not merely mounted on a concrete wall but rather functions as a load-bearing-element. There are unexpected advantages compared to concrete: one such advantage is in the mass of the material, weighing 4 times less than concrete. This makes transportation to the site less costly.

An even greater advantage is the ecological factor: the elements can be produced using relatively little energy and are very effective insulators.

They are also thinner than normal concrete walls. Including insulation the elements are a mere 24.5 cm thick which in turn means less loss of living area. Inside the element is made up of three layers: the exterior surfaces are clad in 2 cm granite veneer reinforced by carbon fibre mesh which is glued to the inner stone surface – between the layers is a 20 cm thick polyurethane insulation layer.

At the top and bottom a special moulding is fitted into the elements. In the case of a multi-story building, this ensures that loads emanating from above are truly absorbed by the elements below and diffused.

Amazingly, the thin waffles do not crack under stress. This is in part due to the insulation layer in the middle and in part to the pretension applied when mounting the carbon fibre mesh.

Like in the case of pre-fab housing, tunnelling for water and electricity are provided in the elements. This reduces building time on site.

Another cost saving source can come from the stone cladding. Stone veneer does not require buffing as it is already covered in highly decorative stone. This is also true for the inner wall.

Since it seems to be in human nature to want an occasional change of tapestry – another interesting variation may be derived from this building method: If the inner walls are destined to be covered in wall paper, material with slight flaws could be used. Thus it would be possible to use waste from the stone block sawmills to produce the waffle elements. The carbon fibre would guarantee stability even in case flawed stone is used.

And that’s not all: if the elements are not damaged when building or during the lifetime of the building, they can be recycled almost indefinitely. Thus the cost of material would be a worthwhile investment in the future, which could be recuperated when the building is dismantled.

In the building’s interior, stone provides a pleasant atmosphere and climate. Stone absorbs humidity and releases it. Thus the unpapered wall could function as a natural humidifier.

Kolja Kuse, Chief of TechnoCarbon Technologies and father of the ideas (see below), has his eye on two main steps. One is to develop suitable lateral connectors for the elements. The second is to find investors for the mass production of the waffle elements so that the technology can prove itself in the test of time as an economically and ecologically wise method of building.

TechnoCarbon Technologies

More ideas for the implementation:

At the Stone+tec in Nuremburg 2009 Kolja Kuse presented a framework beam (see photo below). It is comprised of carbon fibre coated stone strips. According to Kuse the beam is stronger than a steal girder and weighs one third less and does not require the enormous amount of energy to fire the blast-furnaces needed in the steel industry. The carbon fibre can be produced from vegetable oil.

The paper-thin stone and carbon fibre technology has long found its way in the flight industry and is used by the Austrian List Company to produce jet plane flooring.

A luxury ski made by the Swiss zai Company and produced with a CFS-core is said to pleasantly glide over the slope.

In the music instrument construction business CFS has shown positive application results.

The CFS ironing board is unusual, though. The polished surface not only allows the iron to glide over the laundry. The laundry is moistened naturally by the water stored in the pores of the stone. Before beginning with the ironing, the stone is wiped with a wet towel. Then the hot iron passes over the surface, steam is released just like a steam iron would do.

Also promising: CarbonFibreStone (CFS) beams instead of steal.