The first experiences of application of compressed earth block were made in Europe in the early 19th century by the architect François Cointeraux. A system of wooden modules was used where moist soil was placed and compacted with the feet. The first machine, the Cinvaram, built in iron, appeared in 1950, in Colombia, in response to the social housing program in that South American country. This technological innovation came to improve the ancient earth construction techniques, namely the sun dried earth block, known worldwide by the name adobe. This compression machine produces blocks of regular shape, dense and more water resistant than the simple adobes. After the release of this machine, many others have emerged, and several specialized laboratories in the analysis of soils which greatly contributed to the development of the CBE construction throughout the world. This technique is widely used especially in countries of Africa, South America, India and South Asia.
In the production of a compressed earth block, raw or stabilized soil should be slightly moistened and placed in an iron press, being subsequently compressed manually or with an engine machine. Currently there are machines that allow you to make blocks of different shapes and dimensions. Compressed earth blocks are usually stabilized with cement or lime, but you can also opt out by not inserting any stabilisation material. The innovation of the stabilized soil allowed higher buildings, thinner walls, showing greater resistance to water. Using cement as a stabilisation element of blocks, these must be sun dried for four weeks. After this, the blocks are ready to be used as normal bricks, using slurry and mortar with a cement and soil base.
1/ It is a local material, so the production must be carried out on the construction site, this way saving in transport, fuel, time and money.
2/ It is a biodegradable material so the cement is absorbed by Nature within 10 to 20 years.
3/ CBE, by not using firewood for their production, avoids deforestation, preventing forest destruction that in recent years has been decimated due to lack of vision and mismanagement of resources.
4/ CBE is energy efficient since it requires approximately 5 to 15 times less energy consumption than a refractory brick. The emission of pollution will be 2.4 to 7.8 times smaller than that of a refractory brick.
5/ Cost efficiency produced on-site, with natural resources and semi-qualified labour, CBE necessarily implies a cost reduction.
6/ Being produced locally, BCE is easily adaptable to various technical and social needs and cultural habits.
7/ It is an easy-to-learn technology, requiring little technical capabilities. Local communities are able to learn this technology in a few weeks.
8/ CBE easily allows unskilled persons to learn an activity that does not require major technical knowledge.
9/ The BCE production equipment is available from manual to motorized machines that allow for these to adapt to rural or semindustrial production scale.
10/ CBE, as proven over the years, that adapts to different needs and to all kind of costs. Its quality, regularity and style allows a variety of finishes.
Not all soil is suitable for the construction of the CBE, but with some knowledge and experience a number of soils for CBE can be produced. The upper layers of soil and organic soil should not be used for the production of the CBE. Identifying the properties of the soil is essential for making good quality products. Some simple and sensory analyses can be performed after a short training. Cement is used preferably for sandy soils, allowing you to quickly reach a greater resistance to the block. Lime is more easily suitable to clay soils taking, however, more time to harden. The average proportion of the stabilizer is quite low.
1/ Proper identification of the soil is required.
2/ Ignorance of the need to manage the resources
3/ The construction impracticality of large openings.
4/ Low technical performances when compared to concrete.
5/ Poorly trained teams produce low quality blocks.
6/ The soil overstabilization by fear or ignorance, implies additional costs.
7/ The understabilization of the soil results in a low quality product.