Building materials: earth fights back
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CTA. 1996. Building materials: earth fights back. Spore 65. CTA, Wageningen, The Netherlands.
Permanent link to this item: http://hdl.handle.net/10568/47436
Sun-dried mixtures of clay and sand are still widely used in tropical buildings. Despite strong competition from other buildingmaterials such as concrete and cement blocks, which have benefited from the image of being modern and 'European',...
Sun-dried mixtures of clay and sand are still widely used in tropical buildings. Despite strong competition from other building materials such as concrete and cement blocks, which have benefited from the image of being modern and 'European', the advantages of sun-baked and compressed earth are again being rediscovered and appreciated in many countries. Earth - soil - is available almost everywhere and is thus a very economic building material. It can also be long-lasting and for hundreds of years earth has been used in many forms for houses, grain stores and religious buildings. Improvements in traditional methods and the introduction of new techniques, including compression and stabilization, mean that buildings based on soil are adapted to many situations, especially where cost 15 a major consideration. Philippe Gamier, an architect in charge of the Question and Answer Service at the International Centre for Earth Buildings (Centre international de la construction en terre CRATerre) of the Faculty of Architecture at the University of Grenoble, France, says 'Almost all building done in the last 15-20 years in the main African cities has been in solid concrete or concrete blocks. One has to go the smaller towns and rural areas to find a significant proportion of new buildings made of earth and especially of unbaked earth.' Until very recently some development projects, especially in Niger, have even used cement blocks in rural areas for stores or silos. This is in spite of the fact that traditional construction in unbaked earth, or 'banco' as it is known in French, is much cheaper and at least as effective as more expensive materials in ensuring adequate storage conditions. Concrete however, carries the modern image so that 'if money were available, concrete blocks would be even more widespread in spite of their being ill-adapted to tropical conditions', says Gamier. Equally important is the effect of earth blocks on the microenvironment, and especially their heat insulating qualities. This, together with their lower costs, is the main reason for the renewed interest in earth buildings. Development of commercial production There is widespread need for low-cost housing in many parts of Africa, nowhere more so than in South Africa. However, many manufacturers of concrete blocks have ceased production for lack of demand and unbaked earth, together with secondhand materials, is now the major structural element in many townships. In Cameroon, many businesses have gone back to making compressed earth blocks, which are suitable for soils containing less clay than simple sundried blocks. A small quantity of cement may be added to the blocks to make them even more stable and long-lasting. The cement needed is half that of standard blocks and 'those who make the effort to master the technique produce blocks of much better quality than most standard concrete ones, which are often very badly done', observes Gamier. A Centre for Earth Construction Technology (CECTech) was established at Jos in Plateau State in Nigeria in 1992. The Centre encourages the use of earth as a building material and provides information, training and technical assistance. This initiative, designed to promote cheap accommodation, has resulted in a whole 'earth network' motivated and led by the manufacturers themselves. Upstream, mechanized factories produce hand presses for making compressed earth blocks for which the market is currently estimated at US$17 million per year. At Jos, almost 200 earth buildings have been constructed recently and the market is expanding rapidly. Furthermore, it is only nibbling at the de luxe housing market for the comfortably off, who actually prefer this type of construction and whose preference gives the industry its buoyancy. 'Individual initiatives are once again multiplying rapidly and we are seeing a renewed interest in buildings constructed from earth', says Gamier. Several colleges and universities are developing research and training programmes. For example, at Ouagadougou, Burkina Faso, the Regional Water and Rural Equipment Higher Technical College (ETSHER- Ecole inter-Etats des technicians supérieurs de l'hydraulique et de ['equipment rural) has established a programme which comprises specialized training in the manufacture of compressed earth blocks and their use in building, as well as the setting up and management of small businesses. A workshop was also organized by the Industrial Development Centre in Yaounde, in Cameroon, in April, Yaounde, in Cameroon, in April, 1996 to train small business managers in preparing bids for obtaining public works contracts using earth blocks. Making compressed earth blocks is ideally a small business enterprise because of the modest investment needed, especially for the machinery for pressing the blocks. Sun-dried blocks are, however, even cheaper and can easily be made at the village level to supply a very considerable market. Sundried blocks are also eminently suitable for emergency situations. In Eritrea, for example, faced with the need to house half a million refugees, the CRATerre, in collaboration with the German Technical Agency (GTZ) and the Building Advisory Service and Information Network (BASIN), is working at means of training refugees to build houses for themselves. It would be wrong to assume that sundried bricks are used only in the most low cost housing. Almost 50 large and small businesses prosper in the south-western United States by supplying four million sun-dried bricks to the local building industry every year. Indeed, the summer home of the former American President, Ronald Reagan, built more than a hundred years ago, is of sun-dried brick. For further information: Centre international de la construction en terre (CRATerre, Ecole d'Architecture de Grenoble, BP 53, 38092 Villefontaine Cedex, FRANCE Fax: 33 74 95 64 21 The Question and Answer service of CRATerre also acts as a network by putting people in contact with experts in their own areas Construire en terre is a practical, illustrated, 278 page manual on using earth for building. It was produced by the staff of CRATerre and is available from Editions Harmattan at a cost of 130FF Compressed hearth blocks: production equipment. Guide Series Technologies no 5 149 pages. Published and disseminated by Centre for the Development of Industry (CDI) 52 avenue Herrmann Debroux 1160 BRUSSELS.