The history of rammed earth construction – sometimes referred to as pise or pise de terre -dates back thousands of years and can be found in many different civilisations across the world.
According to Wikipedia, “Evidence of ancient use of rammed earth has been found in Neolithic archaeological sites such as those of the Fertile Crescent, dating to the 9th–7th millennium BCE, and of the Yangshao and Longshan cultures in China, dating to 5000 BCE.” In 2000 BCE in China, rammed earth technology was used for a variety of structures, including parts of The Great Wall which are still standing today.
While many rammed earth structures were created for more modest uses, like houses or schools, outstanding examples of earth building include the Great Mosque in Mali, originally built in the 13th Century, and the Alhambra Palace in Spain, both declared UNESCO World Heritage sites. Both ancient and contemporary rammed earth buildings can be found on just about every continent, particularly in Asia, Africa, Australia, Europe and the Americas.
There are three main types of earth building
– adobe, made from sun dried mud bricks; cob construction which uses no moulds or formwork; and rammed earth. All three tend to combine local clay or soil with organic matter like straw, often combined with gravel, lime or chalk – these days a small amount of cement is often added. Rammed earth construction usually uses some kind of formwork – like scaffolding and panels – which are fairly inexpensive materials and can be re-used multiple times.
The construction process also produces a very aesthetically pleasing end product. Layers of different coloured clay can be used to create horizontal stripes and delightful variations in the end result.
There are many advantages to earth building. Most of the materials like, clay or mud, and water are locally sourced so there are no transport costs and much lower carbon emissions.
The materials used are natural and non-toxic and no carbon is produced to manufacture the materials, unlike fired clay bricks, steel, aluminium or concrete.
This makes the materials very sustainable and non-polluting. Currently the construction industry is estimated to produce close to 40% of global greenhouse gas emissions so cutting back on pollutants is a great idea.
Earth buildings provide excellent sound and thermal insulation reducing the need for energy hungry heating and cooling. In addition, earth buildings help to regulate the quality of indoor air as they regulate the air humidity and prevent the growth of moulds and help to prevent allergies caused by highly processed materials.
They absorb excess moisture when the air is damp and release it when conditions are dry. Earth buildings are extremely fire resistant and very durable. They are also pest resistant as, once cured, there are no recesses for
pest to breed or to gain internal access. Little maintenance is required, there’s no painting needed, and walls might just need to be patched or resealed every 10 years or so, if needed.
Earth buildings are very cost effective and little skilled labour or specialised machinery is needed, except perhaps for a plumber and an electrician. Building an earth structure using local labour is also a great opportunity to train and empower the community. Earth building designs are very flexible and don’t need to rigidly conform to architectural plans; rooms can easily be enlarged, added or adapted to suit the owners’ requirements.
There’s minimal waste as only the amount of material needed is produced and any excess can easily be recycled. Once the structure has lived out its lifecycle there’s no waste to dispose of – earth and mud can return to their natural state with no pollution or environmental degradation from dumping.
In a way earth building ties in with a number of other environmental concerns that seek to reduce global emissions like, waste management, recycling, vegetarian and vegan lifestyles, reduced plastic waste and bio-diversity.
SCOPE Zimbabwe (Schools and Colleges Permaculture Programme) recently launched the Chitubu Eco-Village project for sustainable living, youth training and practical demonstrations.
More on this complex discussion in future issues!
Source: S&D ISSUE 68
