Construction using rammed earth has already been done for centuries by several civilizations. And in recent years, this building material has been getting back its well-deserved recognition, as people are now looking for more sustainable material options.
Rammed earth walls are made either by ramming soil into blocks which are then arranged to make walls, or by building whole walls themselves.
a) Highly Sustainable
The process of making these walls involves the usage of completely natural materials like soil, chalk, lime and gravel. It also has an additional benefit of using the locally available soil which uses low energy and produces very little waste.
b) Temperature Control
Rammed earth has the ability to absorb heat during the day and release it during the night. This property greatly reduces the need for air conditioning even during summers. It also helps regulate humidity.
Rammed earth is one of the most durable earth materials. Properly constructed rammed earth walls (with appropriate soil types and constitutions) can stand for thousands of years.
d) Load Bearing Capacity
These walls can bear loads well, depending on the soil. Soil with less clay can bear more load. Additionally, adding cement can increase this property.
e) Requires Less Skilled Labor
Once the technique is observed, it's easy even for semi-skilled and unskilled laborers to work with.
f) Acoustic Property
The thickness of rammed earth walls vary based on local regulations and preferences. But compared to walls built using other materials, they are quite thick, making them suitable for sound-proofing.
Since rammed earth walls are mostly made up of earthen materials like soil and gravel, they are highly fire-resistant.
h) Easy To Maintain And Repair
In case of cracks or blemishes, the soil mixture can be plastered and then sanded smooth. These walls are also termite-resistant.
Rammed earth walls have the natural texture and even colour of the earth. They have beautiful organic textures of the soil that was used to make the walls. Usually, coating or finishes are not given to preserve this look.
a) Soil Type Selection
The durability, strength and load bearing capacity of a rammed earth wall highly depends on its soil type. Poor quality soil selection might affect the building.
b) Not A Good Choice For Cold Climates
Although rammed earth is an excellent option for hot and humid climates for its heat absorbing quality, it is not ideal for colder climates. These walls might need an additional layer of thermal insulation.
c) Erosion Due To Rain And Water-logging
Rammed earth walls might not get washed away, but long exposure to excessive rains can cause erosion. These walls are mostly lifted 225 mm above ground to prevent water damage.
d) Not Easy To Modify
Since rammed earth walls are mostly made as one whole wall, they are not easy to modify or change later on, once the structure is built.
The process of construction of a rammed earth wall is simple but very tedious. Since modifications are hard to make, the room for experimentation and errors are very less.
- Proper soil type, after a thorough analysis and tests is chosen (preferably locally sourced in order to reduce transportation charges).
- Make sure to have at least on skilled labour is available.
- Required proportions of gravel, sand, clay and additives, if required, should be added to the soil.
- This mixture is dampened and poured into a wooden framework of the required shape and size, where it is rammed.
- The framework should be well-braced and clamped properly to prevent leakage or deformation.
- The mixture compacts to almost 50% of its original volume.
- When one batch is over, the same process is repeated and the Wallis gradually built.
- The wall is then left to cure. The compressive strength of the wall increases with the time it is given to cure.
- Once the wall becomes strong enough to stand without the framework, the latter is removed.
- To give a better finish, brushing and cleaning is done. Molding and carving patterns are also an option.
Rammed earth is probably one of the most sustainable options in the market. Although it might not be the best option in cold or rainy climates, in a country like India, which is majorly hot and humid, it is a very good choice.
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