In Western countries, the building sector is energy efficient and a strong emitter of greenhouse gases. In addition, build a house engulfed household budgets. The concept of a house with earth bags makes it possible to use local products (land found on site) and at a derisory cost . The bags can be filled with soil, sand (or other material), depending on locally available resources. A bag of earth or sand, it does not move at all (there are several systems for the adhesion of the bags between them is total barbed fez wire, velcro effect etc.), the house is very stable .
The compacted and dried earth (the drying can be accelerated in the ecodomes by making a fire inside the completed construction) becomes very hard , of the brick / ceramic type. The material of the bags used (polypropylene) by CalEarth is very resistant. A layer of protective coating is then added to protect from rainwater.
This house, a real bunker, is almost indestructible. The bags of earth or sand are also used by the army as anti-shell shelters, but also to fight against floods. The ecodom (“SuperAdobe” technique) is a fully recyclable house , insulating , anti-seismic , and at a cost almost zero. It is also resistant to cyclones and floods . It is not afraid of insect attacks (termites) or mold . The earthen house is as solid as the earth itself
As in churches, the dome structure allows, by gravity, the maintenance of the entire structure. Straight constructions (with an ordinary roof) are also possible and are also very solid. The thermal inertia of the construction is very good. Ditto for thermal insulation (the walls are thick). The plastic bags prevent upwelling of the soil by capillarity.
In highly deforested sectors (Haiti, sub-Sahelian Africa, etc.) the EcoDome concept brings a major advantage: its construction does not require wood (no framework).
The father of the EcoDome concept is Nader Khalili, an American architect of Iranian descent (he studied in Iran, Turkey and the USA), who originally designed skyscrapers. Then, following a request from NASA, he developed a house concept for space missions on the moon , using locally available material: lunar dust. Nader Khalili has spent 5 years riding motorbikes through the Iranian deserts, helping local people to build earthen houses and improving their revenues year after year (Iran is a highly seismic country). He received the Aga Kahn Architecture Award in 2004. In 1988, an experimental village was built north of Los Angeles, in a desert region. On the environmental and socio-economic levels, that is to say at all levels, the concept is frankly great .
From the moon to the earth …
Nader Khalili is an Iranian-American architect who worked on lunar architecture in the 1980s and developed sandbag constructions, which he calls “Super Adobe”.
The United Nations is also interested in the principle. And indeed, the High Committee for Refugees (UNHCR) and the Program for Development (UNDP) have sent representatives to Hesperia to study the achievements of Nader Khalili, before using them to shelter refugees from the earthquakes in Iran in 2002 and in Pakistan in 2005. “
Plan of the file:
Part 1: Home made of earthen bags / Introduction Part 2 – References Part 3 – Which plastic for bags? Part 4 – Constructions around the world Part 5 – Budget
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House made of earth by Natureconstruction
House in earth bags
The construction of earth bags is based on the use of bags filled with soil and barbed wire. It is very inexpensive, but requires manpower.
This natural construction technique has evolved from the military construction of ‘bunkers’ and methods of temporary flood control dikes. The technique requires very simple building materials: solid bags, filled with soil and other inorganic materials generally available at the site (such as sand, gravel, clay or crushed volcanic stones). The walls are gradually put in place by filling the bags staggered (like masonry).
Walls can be bent for lateral stability, forming round pieces and domed ceilings like an igloo. For buildings with straight walls of more than 5 m. in length, foothills should be added.
The building is stabilized by placing barbed wire between the rows. One can also use twine wrapped around the bags to link the rows between them, this serves to maintain the overall structure and strengthen it. Reinforcing rods can be hammered into the walls, especially at the corners and near openings.
The structure is usually finished with plaster, stucco or bricks, both to evacuate the water and prevent any degradation due to the action of the sun. This construction technique can be used for emergency shelters, temporary or permanent housing, barns and many other structures.
Various types of roofs can be used. Dome roofs are extensions of the wall that form vaults or cupolas. Arches and earth domes are very inexpensive to build, but making them impervious is a complex and expensive process in humid areas. It is easier to build rectangular and circular buildings with wooden or metal roofs in the local architectural style.
Windows and doors can be formed with a traditional masonry lintel or with corbelling or arcade brick technique, usually for temporary forms. The light may also be introduced through skylights, capped glass tubes, or bottles that are placed between the rows of bags during construction.
Foundations are often made of bags of gravel, or reinforced cement. Bags of soil should be placed at least 15 or 30 cm above the ground (this is not the case for cement) It is important to use cement close to the ground before stacking the bags. gravel, sand, or earth.
Types of bags
The most popular is made of woven polypropylene, such as the type often used to transport rice or other cereals. Polypropylene is chosen for its resistance to water damage, rot and insects.
Non-organic material is generally used, but organic materials (such as rice balls) can be used. The most common filling material is clay with clay (between 5 and 50%). The bags of compacted earth form structural units, but can not withstand prolonged soaking. Sandbags and gravel can withstand prolonged flooding. But most of the time, the sandbags are not strong enough without temporary bracing and the addition of structural skin. The soil can be stabilized with cement, lime or bitumen to enhance watertightness and strength (this is not necessary for structural plaster.
Thermal insulation properties are important in countries with significant temperature variations. Crushed volcanic rock, pumice or rice, hulls have very good insulation values (better than clay or sand). But we must not use organic materials that putrescible or biodegradable for load-bearing walls. They can be used as filling between stations. In the absence of light gravel, plastic waste can be used as filler insulation in soil bags.
The thermal mass properties of the filler material are important for climates that experience severe temperature changes every day. The ideal solid earth walls are an ideal solution for mild climates thanks to the effect of inertia. The earth or sand has excellent heat retention properties, and when the insulation of the exterior of the house is well made, these materials are a good solution for passive solar buildings in cold climates.
When the filling contains a lot of clay, plasters made with lime or only earth are better. An earth wall must breathe and dry out, especially in climates where temperatures drop below freezing.
In hot climates, cement stucco can be used. Cement stucco is a good solution on stabilized soil near the ground: the rain infiltrates inside and then flows back.
But, often plaster of lime or earth is the best finish. The cement is too rigid and does not expand or contract like a wall of soil. We can start the finishing with soil and use lime on top. In addition, it is easier to repair lime.
Reinforcement for risk areas
First, choose a solid location for the building. The regular shape of the structure and the separation of the walls are two important criteria. International standards exist for bracing for earth construction in different types of seismic hazard zones. Reinforced cement buttresses with mortar anchors and barbed wire may be used to strengthen the strength of public buildings in seismic hazard areas.
The angles should be reinforced with barbed wire and a mesh of nylon fishing net should be used under the plaster. It is important to protect the bags from sunlight with plaster quickly. Another imperative is to finish the wall at the top with a reinforced concrete connecting beam.
As with the geo-textile retaining walls, a well-made earthbag construction can withstand earthquakes because of its flexibility.
On raw earth, the rammed earth, the terracotta (brick) have qualities quite remarkable, in particular, at their thermal inertia of 12h (which dampens the temperature variations). The rather average thermal insulation characteristics of the earth (lambda = 0.850) can be improved by adding insulation such as straw or wood chips during construction.
The earth is an inexpensive material, it adapts perfectly to the environment and once cleared of its most important impurities (pebbles, …) and mixed with water and / or straw, it can be used for the construction. The latter is as resistant as a stone construction
Use of raw earth
- walls of houses: A mud wall keeps the summer cool and accumulates heat in the winter.