Strong supporter of hemp, Laurent Charvoz has nothing of a halluciné. Graduated in geotechnical, holder of a DEA in geology, a researcher time to the Centre for advanced studies of the construction, the construction company Chief knows by heart the formulation of the materials it uses on its sites. And, for this thirty-nine years Mason, former engineer methods in Bouygues and Vinci, hemp concrete is a material for the future.
Until then reserved a customer informed and often committed, from hemp building is on the rise ("Les Echos" from September 30, 2009). Because hemp insulates without stifling, this easy to grow plant used for ropes, mulching or the cigarette paper, makes obsolete double-flux breakdowns. Its failure: used alone, the hemp does not support the weight of a roof. Where the idea of associating it with a concrete innovative filter the air.
"For thermal reasons, the classical block, which is a poor insulation, happen gasping for air in twenty years", predicted Lawrence Charvoz, CEO of Martin BTP, which already built more than 800 prefabricated houses or public buildings (hospitals, schools...) in cement in the centre of the France. Looking for an alternative and more efficient solution for isolation, it has developed with the laboratory of materials of the University of Poitiers "sandwich panel" patented, combining a concrete Lite database pozzolana (a volcanic rock) and lime and hemp. To the project, he launched an Office of studies, natural houses in concrete of hemp (MNA), funded by its own funds and a contribution of 120,000 euro Oséo.
Waiting for validation
The idea is to achieve the four load-bearing walls of a house in a factory, with a time of drying of about six weeks. "We have not tabled formulation, just the process of implementation", said Laurent Charvoz. "It is an improvement of the ancestral house at COB consisting of clay, straw, and water," adds Jean-Hugues Thomassin, Professor Emeritus of the University just maliciously.
Control Panel incorporates a metal structure for the build. Chemical sealing between light-weight concrete and hemp - the heart of innovation - is complete with screws placed in the corners. "We are working on the technique, and nothing prevents to imagine two, even three, floors concrete of hemp in the near future", forward Laurent Charvoz, also designed the small buildings market.
Other innovative techniques already use hemp as insulation. "In our case, this is the major element in the construction, and it requires validation by the scientific and technical building Centre, distinguished Laurent Charvoz.". The approval of the CSTB to begin the ten-year guarantee. "However this Sesame issued by insurers builders is essential. The folder is in the statement.
A first development using this material should see the day in Sologne, in the commune of Neung-sur-Beuvron (Loir-et-Cher). For this project, marine construction joined the law firm of experts in thermal engineering Energies Nantes, an architect and a promoter responsible for the marketing. The first two wings of this écolotissement of thirty lots will emerge from Earth to the re-entry, about 1.400 euros m. Either a pavilion of 100 m at 140,000 euros, without field.
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