Brick walls have been in use for several thousands of years; India and other near eastern countries first started building block walls about 5000 years ago. The ideas behind the way block walls and bricks are made have changed little over the years. Even the size of bricks has stayed relatively unchanged. Bricks designed for the construction of brick walls can also be referred to as compressed earth blocks, or CEBs. As the name implies, bricks are made by compressing a type of earth such as shale or clay. The actual shape of the brick can be produced in two different ways: the soft method and the stiff mud process. The soft method is when the clay is compressed into a form. The other way of shaping brick is the stiff mud process, where the earth is pushed through the form and then cut to the desired size. Either way, the brick needs to be powerfully compressed. The more a brick is compressed, the more it adds to the durability of the final brick wall. A brick that has been highly compressed will absorb less water and can be used in outdoor applications where the brick wall is exposed to rain and other weather conditions.
The compressed earth block is the modern descendent of the molded earth block, more commonly known as the adobe block. The idea of compacting earth to improve the quality and performance of molded earth blocks is, however, far from new, and it was with wooden tamps that the first compressed earth blocks were produced. This process is still used in some parts of the world. The first machines for compressing earth probably date from the 1 8th century. In France, Francois Cointeraux, inventor and fervent advocate of “new pise” (rammed earth) designed the “crecise”, a device derived from a wine-press. But it was not until the beginning of the 20th century that the first mechanical presses, using heavy lids forced down into moulds, were designed. Some examples of this kind of press were even motor-driven. The fired brick industry went on to use static compression presses in which the earth is compressed between two converging plates. But the turning point in the use of presses and in the way in which compressed earth blocks were used for building and architectural purposes came only with effect from 1952, following the invention of the famous little CINVA-RAM press, designed by engineer Raul Ramirez at the ClNVA centre in Bogota, Columbia. This was to be used throughout the world. With the ’70s and’80s there appeared a new generation of manual, mechanical and motor-driven presses, leading to the emergence today of a genuine market for the production and application of the compressed earth block.
Since its emergence in the ’50s, compressed earth block (CEB) production technology and its application in building has continued to progress and to prove its scientific as well as its technical worth. Research centers, industrialists, entrepreneurs and builders have developed a very sophisticated body of knowledge, making this technology the equal today of competing construction technologies. CEB production meets scientific requirements for product quality control, from identification, selection and extraction of the earth used, to quality assessment of the finished block, thanks to procedures and tests on the materials which are now standardized. This scientific body of knowledge ensures the quality of the material. Simultaneously, the accumulated experience of builders working on a very large number of sites has also enabled architectural design principles and working practices to emerge and today these form practical points of reference for architects and entrepreneurs, as well as for contractors.
The setting up of compressed earth block production units, whether on a small-scale or at industrial level, in rural or urban contexts, is linked to the creation of employment generating activities at each production stage, from earth extraction in quarries to building work itself. The use of the material for social housing programs, for educational, cultural or medical facilities, and for administrative buildings, helps to develop societies’ economies and well-being. CEB production forms part of development strategies for the public and the private sector which underline the need for training and new enterprise and thus contributes to economic and social development. This was the case in the context of a program on the island of Mayotte, in the Comoro islands, for the construction of housing and public buildings, a program today regarded as an international reference. The use of CEBs which followed the setting up of an island production industry proved to be pivotal in Mayotte’s development, founded on a building economy generating employment and local added value in monetary, economic and social terms.
CEB represents a considerable improvement over traditional earth building techniques. When guaranteed by quality control, CEB products can very easily bear comparison with other materials such as the sand-cement block or the fired brick. Hence the allegiance it inspires amongst decision-makers, builders and end-users alike.
CEB technology has made great progress thanks to scientific research, to experimentation, and to architectural achievements which form the basis of a wide range of technical documents and academic and professional courses. A major effort is now being devoted to the question of norms and this should help to confer ultimate legitimacy upon the technique in the coming years.