Earth architecture draws attention to a variety of innovative projects and employs unique forms through construction. The techniques used to build with earth are ancient and have made an impact all around the world. While earth as a material took a back seat with the arrival of concrete in the 1950s, it is back in demand as it provides ecological as well as aesthetic benefits.
The misconceptions regarding earth as material ceases to exist as earth architecture has begun regaining its momentum. Modern age architects are building and creating with these ancient methods and are modifying them to meet the needs of the present. Creating with earth has always been sacred and loved by many.
To get a quick start into the world of earth architecture, here are a few construction techniques that are used in the field.
1. Cut Blocks
In this methodology of construction, soils that are cohesive and contain concretions of carbonates are cut in the form of blocks that are used as bricks or stones. These blocks are typically found in tropical areas where the lateritic soils act as materials for construction. Lateritic soil is usually found in two stages – Soft soil, which hardens over time due to exposure to air, and a hard crust which has hardened over the years. In regions where the soil is not cohesive enough, a mixture of topsoil and grass are used to create blocks that are stacked on one another.
2. Poured Earth
Poured earth is similar to concrete, in the sense that both materials are mixed and poured into a framework. The main factor that sets them apart from one another is the aggregate in both materials i.e. sand/gravel for concrete and ordinary soil for poured earth. The ideal soil for poured earth should have low clay content. One of the drawbacks of this technique is the high water content in the soil. It induces shrinkage once the form dries resulting in cracks.
Developed by Iranian Architect Nader Khalili, superadobe is a type of earthbag construction. The technique makes use of long or short sandbags that are filled with moistened earth and arranged in layers or coils. Barbed wires are placed between each layer and serve as both reinforcements as well as mortar. The structures built using this technique also employ vaults and corbelled arches as well as domes to create sturdy shells.
This particular technique has been used all over the world for thousands of years. Sun-dried clay brick i.e. adobe is one of the oldest building materials used by mankind. Adobes are made of thick malleable mud that is often mixed with straw and is either shaped by hand or in wooden molds. They can be assembled easily with the adobe mix used as a bond for the individual bricks as well. Adobe structures are extremely durable and the material has a high thermal mass. However, structures made of adobe are susceptible to earthquake damage if they lack proper reinforcement.
Cob construction is an old technique that involves the layering of a mixture of clay and straw. The technique does not make use of mortar or a framework, rather it uses hands and feet to attain a form. Hence it lends itself to organic shapes such as curved walls, arches, and niches. Due to its porous nature, cob is quite resistant to weathering and can withstand long periods of rain without weakening.
6. Rammed Earth
Rammed Earth structures are formed from the soil that is damp enough to hold together. The earth is mixed with water to form a mixture which is then tamped between shutters using manual or pneumatic rammers. The shape of a wall constructed using the rammed earth technique is based on the shuttering used. Rammed earth walls are usually left as they are due to the aesthetic strata pattern that develops from ramming. The walls constructed can be sculpted to an extent while the earth is damp. Rammed earth has a lesser shrinkage ratio, long life as well as strength when compared to other techniques.
7. CSEB (Compressed Stabilised Earth Blocks)
Compressed earth blocks were attempted in the early days of 19th century Europe. The soil, either raw or stabilized is moistened slightly, poured into a steel press, and then compressed with a manual or motorized press. The blocks can be made raw or stabilized with cement or lime. The addition of stabilizers allowed construction of higher and thinner walls that have great compressive strength and water resistance.
8. Wattle and Daub
Wattle and Daub are one of the most common infill wall techniques. It has been used for 6,000 years at least and is still used significantly in several parts of the world. The timber forms a woven lattice and is plastered with earth mixture that usually consists of wet soil, clay, sand, animal dung, and straw.
9. Shaped Earth
Similar to how a potter shapes mud into pots, the shaped earth technique directly shapes the plastic earth without a mold or formwork. The three factors that play a key role in this method are the quality of the soil, its preparation, and water consistency. A great advantage of this method is the minimal usage of tools as well as the labor force. Shaped earth allows fluidity in architecture to a great extent and the few limitations to this technique are understanding the soil quality as well as controlling shrinkage once the structure dries.
10. Straw – Clay
In this technique, clayey soil is mixed with water and then added to straw. Earth helps bind the straw together. Straw clay is easily adaptable for prefabrication of wall panels, flooring, and large bricks. It serves as substitutes for drywall as well as insulation and allows for light-weight construction with good thermal properties.