(March 2011) A sort of flying carpet was presented at the Marmomacc 2010, specifically at the Stand of La Pierre de France: Designer Jean-Michel Wilmotte covered the presentation in hall 11 with a wave-shaped roof reminiscent of One Thousand and One Nights. But note that this is no ordinary corrugated sheet. This is millimetre-thin limestone on an aluminium honeycomb.
Combinations of thin stone and reinforcement material have been on the market for some time. But until now it was not possible to bend the construction. The know-how was developed by Stone Performance the technology subsidiary of La Pierre de France. The flying carpets are produced in Portugal.
Part of the know-how lies in the choice of adherent and the proper temperature to bring it into shape. Abid Farsak, Director of Stone Performance, reveals yet another aspect: „One has to know which stone to use and which direction is best for the bend; concave and convex need to be treated individually.“ When flexing the stone into a concave shape, it comes under pressure load – one the strengths of stone. „We have managed to bend a module of 6 mm thick stone on a 20 mm thick aluminium honeycomb reinforcement layer to a radius of 3.4 m“, according to Farsak, „feasibility is dependant on the mechanical properties of the stone and on the production process whereby we constantly surpass our own limits.“
It is not necessary to treat the thin stone with resin. According to Farsak: „It is our aim to keep the material as natural as possible.”
This opens a whole new realm of possibilities for architects: with the SPP-Technology – Stone Performance Process i.e. thin stone combined with honeycomb on top of a sub construction for affixing it to the wall – even circular constructions can be accomplished without excessive material costs. Cases in point: Baku’s boutique of Yves Saint Laurent or star architect Jean Nouvel’s suspended ceiling in the Champs Elysées.
„Stone-Performance frees architects from the constraint of stone slabs“ according to Abid Farsak. „Façade design is no longer about management of joints.“ He describes the new „modern“ properties of stone slabs like this: „oversized, light-weight and easy to fasten“. All the while, durable as ever.
Forerunners of the flying carpet are the thin stone sheets on various carrier materials available and marketed by a number of producers. Their main advantage is in the light weight: what with 15 kg/m² their weight is merely one sixth that of stone slabs. This also makes manufacturing of large surfaces in factories feasible allowing prefabrication and efficient assembly on site.
Finally flexed plates allow manufacturers to spare raw material: previously circular pieces had to be cut from massive blocks with much waste.
But: are millimetre thick plates still definable as stone? What about the natural qualities of stone?
The answer is dependant on taste. There is no absolute definition of how thick stone must be to be defined as stone: Is a façade slab 3 cm thick still stone? If not, then stone tiles of 1 cm thick certainly would fail the test.
One more word to La Pierre de France: This is a holding of a number of stone companies in France founded in 2008. Their aim is the advancement of product innovation, technical development and marketing. As the French magazine „Pierre Actual“ (10/2010) states, La Pierre de France comprises some 40 quarries and 6 distributers. When the article appeared in November 2010 an export office and a consortium in road construction joined the ranks.
Photos: La Pierre de France