Rammed earth basically works like the formwork of pouring a concrete wall. But instead of concrete, one uses soil from the site. The construction of an entire wall begins with a temporary frame, denominated the "formwork", which is usually made of wood or plywood, as a mould for the desired shape and dimensions of each section of wall. The form must be durable and well braced. The material is tamped down. This can be done with sledge hammers by hand or with a pneumatic device. Then the form is pulled off and voila – a stable wall is created.
Edifices of rammed earth are thought to be more sustainable and environmentally friendly than popular techniques of construction. Because rammed-earth structures use locally available materials, they usually have low embodied energy and generate very little waste. Rammed earth has great thermal mass and acoustic properties .Throughout the day, as an exterior wall is exposed to the sun, it absorbs energy, and then slowly releases it at night.
“Rammed earth technique is created directly on site and requires skilled labor to complete it. This labor is not easy to locate" says Jeremie Gaudin of the Made in Earth Collective, India. Rammed earth is easy to do, but difficult to do well. Made In Earth is an architecture studio and construction practice based in Bangalore, India. They promote an architecture that is closer to the people, the environment and the resources of a place. Their team works with natural building materials and techniques with a taste for experimentation and innovation.
Meror Krayenhoff, inventor of ‘SIREWALLl’, is one of the top 5 experts in the world on rammed earth. Structural Insulated Rammed Earth – SIREWALL, is a structural sandwich wall system typically 18″ to 24″ thick where local soils combined with 6-10% cement are compacted on either side of a hidden insulation core. It is then stabilized with compacted earth and rebar, with 4″ of rigid insulation hidden in the center of the wall (rebar is used in seismic zones). The world wide tradition of rammed earth construction has shown that it is possible to achieve strong majestic buildings that have withstood the test of time.