Rammed earth – the building material of the future
Martin Rauch, Lehm Ton Erde Baukunst GmbH
Mag. Art. Martin Rauch
Founder & Managing Director Lehm Ton Erde Baukunst GmbH
Lehm Ton Erde Baukunst founder, managing director, and clay building pioneer, Martin Rauch, has been committed to rammed earth construction for more than 35 years. During this period, several hundred rammed earth construction projects have been realised, at various scales and with an international scope. Cooperation with renowned architects and numerous awards underline the company's long list of references and expertise. With the construction of the ERDEN Werkhalle, a production facility for prefabricated rammed earth elements and soon to be the company's headquarters, the company will soon specialise in the industrial prefabrication of rammed earth elements.
Clay is a building material that is available almost everywhere and can be used in many ways. If you design according to the material, almost anything is possible. It is therefore difficult to understand why chemical stabilisers such as cement are used in half of rammed earth projects while asserting sustainability in construction. With rammed earth construction, thicker walls are usually necessary. When accounting for this volume, the addition of chemical stabilisers corresponds approximately to the same amount of cement as top quality reinforced concrete. Furthermore, these chemical stabilisers largely negate the technical advantages such as diffusion, absorption of odours, moisture regulation, and recyclability. Martin Rauch and his team rely on and trust exclusively in 100% earth in their planning and implementation of rammed earth projects and deliberately avoid chemical stabilisers.
The use of earth in outdoor areas is always subject to certain erosion behaviour. Due to the liveliness and colourfulness of this natural material, a wide variety of erosion behaviour can be observed and, allow an ideal natural and characteristic ageing process. Water solubility, the supposed weakness of clay, is its strongest virtue. The climatic advantages of this building material depend precisely on this property. The key is to control this natural erosion - this is known as "controlled erosion". By installing erosion brakes known or “checks” in the form of horizontal layers of brickwork or flush, integrated layers of trass lime mortar, the flow of the water down the wall is slowed down. After the first few years, the outermost, fine layer of clay is washed out. The bricks protrude further and the wall appears rougher. The remaining clay bound to the course aggregate now lies deeper in the wall and swells up when it rains. This swelling of the clay prevents water from penetrating deeper into the wall and further eroding the wall.
The realisation of large scale projects like the Ricola Herb Centre in Laufen, Switzerland and the Alnatura Campus in Darmstadt, Germany have demonstrated the potential of industrial prefabrication in earthen building. The production machine affectionately known as Roberta, which was specially developed 10 years ago by Martin Rauch together with a local mechanical engineering company, is the keystone of the industrial prefabrication process. The advantages are obvious. The industrial production process can be carried out independently of the weather and with considerable time and cost savings. The assembly of the elements on the construction site can be integrated more optimally into today's construction processes and tight schedules.
The know-how in industrial prefabrication accumulated during the last 10 plus years will now be concentrated at the company’s new base of operations. With the construction of the ERDEN Werkhalle, a production site with infrastructure tailored to rammed earth construction processes has been created. Through current research projects, the Lehm Ton Erde Baukunst team is already working intently to standardise and certify prefabricated rammed earth elements in order to revolutionise the building sector with an ecological and sustainable solution for the future.
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