 | BASIN-News No. 2 - July 1991 - Building Advisory Service |
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The compressed earth block
from craft workshop to industrial production
Illustrations:
1. Modernizing building with earth an essential prerogative
The current demand for housing in developing countries is enormous. Recent statistics have shown that for the urban population of Africa alone no less than 36 million homes need to be built between now and the year 2000.
In development plans, unbaked earth is so far rarely included amongst the materials which might meet this demand. And yet, 30% of the world's population, or nearly 1,500 million human beings, live in earth buildings. In terms of jobs, the earth construction sector is far and away ahead of other building materials, but these jobs mostly form part of the informal sector, the economic importance of which is rarely taken into account. The predominance of earth in the informal and rural building sector can be explained by the fact that the investment required for both producing earth building materials and using them is very low. Earth is one of the easiest raw materials to process for use in building. Other materials which are often considered to compete with earth, such as fired bricks or sand-cement blocks, can also be produced with low investment, but these labour under other particular constraints high energy consumption for fired bricks, and for cement blocks, the cost of cement, which requires very heavy investment to produce.
On the other hand, this low investment requirement is counter-balanced by a fairly high consumption of labour. The constantly increasing cost of labour in Europe since the turn of the century has led to the virtual elimination of building with earth in this part of the world. Moreover, the various different earth building materials are in general relatively little processed. This is no problem for simple constructions or in a rural context, but is poorly suited to the context of more structured production and distribution chains or for more sophisticated buildings. Rapid urbanization, resulting in the rapid structural evolution of building production, distribution and utilization chains, is the second reason for the disappearance of building with earth in Europe, and the primary factor in its disappearance in the formal economic sector of developing countries where labour costs, which remain low, should have enabled it to survive.
In order for earth as a building material to survive, both in Europe and in urban areas of developing countries, it must therefore be more highly processed and have better labour productivity.
This change can be achieved with a minimal investment in equipment and technical sophistication, but at the same time this investment rapidly bears fruit and allows building with earth not only to survive, but also to develop further, even in highly industrialized contexts. Such, for example, has been the case in the USA, where more than 176,000 earth houses were to be found in 1980, mainly in the south-western states. In California, earth building is increasing at the rate of 30% per year. In New Mexico, in 1981, 48 adobe factories were producing more than 4 million blocks a year. It is thought that the same number again is produced annually by self-help builders. France is witnessing increased use of wattle and daub construction, which had been completely abandoned for several decades, since its production has been mechanized and quality improved through a scientific approach to the material. Taking account of the needs of building material distributors has also greatly helped its adoption by building companies.
If investment is required to ensure a place for building with earth in the modern economic sector, it could be thought that this would in the end eliminate the principal advantage of earth, which is precisely that it is usable without investment. In practice, however, the production of earth building materials remains competitive thanks to the wide range of levels of investment possible. Thus industrial large-scale production units can be setup, but equally so can craft work shops, which is not the case for all production processes, including that of prefabricated reinforced concrete elements which require very high investment from the outset. In the case of earth building materials, the nature of the production line used is dictated by the means at the disposal of the entrepreneur and by market needs, and not the other way round Hence the very widely I differing levels of investment to be found in different cases, even within the I same overall context; in the USA, for example, small family "cottage" industries are to be found alongside industrial production units.
The great strength of earth as a building material is no longer its low initial investment requirement, but its flexibility with regard to the conditions necessary for the I creation of production businesses.
2. Compressed Earth Block technology
If we compare the main ways of building from the point of view of the level of investment each requires, it is clear that where investment capacity is weak, masonry building is an appropriate building system, given that as with the production of earth building materials -it does not necessarily require high initial investment. It was therefore logical for first steps in modernizing building with earth to focus on the production of small masonry elements.
Research and development with this in mind began in the 50s. Most typical of this approach remains the work of the Raoul Ramirez, an engineer, and his team; in the context of a rural housing improvement programme in Columbia, he moved from traditional techniques for moulded unbaked earth blocks (adobe) to a new technique for the producing blocks by compression. The resulting material had regular dimensions, a very pleasing appearance and a higher density. The goal had been achieved with reduced investment, enabling nevertheless greater processing of the product, the end-product had a better finish, was capable of being integrated into more highly organized building production and distribution chains, and was better suited to satisfying the aspirations of rapidly evolving societies than traditional materials.
The technique spread and was called by various names depending on local contexts, before now coming to be known as the "compressed earth block", often abbreviated to CEB.
a manual earth block press
The use of a press, the famous Cinva Ram, was the first investment introduced for this bringing up-to-date of traditional techniques. Although simple, and very reasonable in cost, it was still something new for skilled workers used to working with a very few simple tools.
The second investment was in technical skills. The ultimate quality of the material depends not only on the use of a press, but also on other parameters, including soil selection, water content etc. Reliable data had therefore to be established for these parameters. The CEB technique became rapidly associated with stabilization, which consists in mixing an additive to the raw material in order to improve the characteristics of the end-product or to enhance particular characteristics. This has in fact sometimes led to certain confusion of terms, and CEBs have sometimes mistakenly been referred to as SEBs, or Stabilized Earth Blocks.
3. From craft workshop to industrial production
The first pioneers of CEB technology sought first to ensure its adoption in the informal sector and in rural contexts. Technical solutions put forward therefore required only very low investment. But actual experience shows inescapably that in the informal sector, investment, however low, is an abstract notion, with the result that even when craftsmen take the initiative to acquire a press, all too often the investment in technical skills required (training, respecting basic quality parametres etc.) is neglected. The production of CEBs in the informal sector still goes on, however, but the price paid is the often debatable quality of the materials produced. Moreover, the volumes produced in this sector are quite inadequate to meet the needs of organized distribution chains.
a mobile motorized earth block press
The future of CEBs therefore lies in areas where progressive investment, in both equipment and technical skill, is possible, i.e. in businesses within the modern economic sector, and more specifically in small and medium-sized private enterprises. Flexibility and the capacity to adapt to different contexts indeed characterize this technology the greater the size of the enterprise, the more this capacity to adapt will diminish and the more the CEB will lose its advantages over other materials. This quality of flexibility again favours private enterprise, rather than public companies or cooperatives, where management structures are often inflexible.
The first craft brickworks were followed by companies of all sizes, from the smallest of workshops equipped with manual presses to large automated industrial production units. These businesses sprang up in most widely differing contexts, always adapting themselves to local conditions, be it in India, Africa, the USA, Australia, and now Eastern countries. In explaining their interest in this technology, entrepreneurs often point to the fact that it enables them to tune the initial investment to their financial means, to their preferences for the way the work is to be organized, and to the constraints of their sphere of activity.
4. Investment for the future
Investment in equipment has been reflected in the development of a very wide range not only of compression equipment, but also of peripheral equipment enabling complete production lines to be put together with equipment specifically designed for this purpose. Since the development of the Cinva Ram, a very wide range of presses has appeared, reflecting the evolution of the technique in favour of organized companies. Over the last ten years, a list has been compiled of some two hundred different models of presses, with correspondingly different financial investment requirements, ranging from 2,000 to 40,000 000 French francs.
The quality and increasing diversity of the equipment available has also enabled diversification and improvement in the quality of the end-products as well as the production of widely differing shapes which are suitable for widely varied masonry work. The enlarged building potential of the CEB is a major consideration when choosing.
As for investment in technical skills, this is apparent in the increasing demand for training, by decision-makers as well as by production technicians. The University has now begun to integrate building with earth as a discipline in its own right, and specialized courses have now been running for five years for post-graduates in other disciplines, i.e. graduate engineers or architects from various European universities and colleges.
This investment in technical skill is also supported by scientific and technical research both on the building materials and on production and application methods.
The underlying approach to problems is no longer empirical, but methodical and scientific. Every year several research theses on one or other aspect of the production of compressed earth blocks are submitted and professional meetings are regularly organized on building with earth as a modern technology.
Technical investment also means establishing a suitable system of standardization. In the informal sector, where the producer of building materials can communicate directly with the end-user, there is no need to create technical references documents. By contrast, in more structured building sectors, which have a greater number of intermediate actors, (producers, wholesalers, retailers. distributors. entrepreneurs quality control experts etc.) the need for technical reference documents is essential. The use of documents devised for other materials has proved to be very counter-productive mechanical performance requirements are unnecessarily high or on the contrary inconsistent. Establishing standards is not intended to penalize producers, but rather to promote high quality and thus open up markets for earth building materials by increasing confidence amongst potential buyers. The establishment of standards, and more generally the promotion of "quality assurance" is underway, thanks to the efforts of organization for regional standards such as the African Regional Organization for Standards (ARSO) and international organizations such as the United Nations Organization for Industrial Development (UNIDO), the United Nations Centre for Human Settlements (UNCHS), and the Commonwealth Science Council Service.
This technical and scientific investment is also supported by interprofessional organizations such as the RILEM TC 96 EB / CIB WC 90 Committee "Earth Technology for Building Construction".
5. Joint actions, the key to success
The future of CEB lies not only with business enterprise, but also with national development strategies. These rest by definition on the search for coherence in national investments. Many developing countries have difficulty in raising the important investment required by a cement works or a prefabricated elements factory.
On the other hand, national capital can be directed towards material production chains such as those of the CEB. It is therefore logical for institutions to encourage material production chains such as those of CEB, since the role played by entrepreneurs goes beyond the context of their own companies and contributes to the national economy, The initiatives of entrepreneurs are thus increasingly supported by national institutions and international organizations. The contribution of these institutions and organizations is mainly of a financial nature but is more and more aimed at being part of a coherent framework of support for technical, material and financial investment.
a medium scale integrated unit
a semi-industrial unit
Currently the most promising approach to ensure the success of projects is that of joint actions between local entrepreneurs and technical organizations or production equipment manufacturers. This is because mastering production operations is not in itself enough; every other aspect of the setting-up and survival of a modern enterprise must also be mastered. With his partners, the entrepreneur, until now often on his own, can at last find all the help he needs to prepare his feasibility study, set up his production line, market his products, or have opportunities for technical and financial training. Funding organizations are in fact increasingly tending to favour this formula and allow particularly favourable conditions for the financing of projects submitted by joint partners.
6. Joint actions, an approach underway
Links between potential partners can only occur if there are ample opportunities to make contact; in this respect, mention must be made of certain events organized with this in mind such as SICAD (the Intemational Fair for Cooperation) which was created with this sole objective.
In the field, examples can be found in joint programmes led by investment divisions of the United Nations Organization for Industrial Development (UNIDO) and the Centre for the Development of Industry (CDI, which is body of the European Economic Community) in collaboration with CRATerre-EAG. In the first instance thanks to field missions local industrialists have been identified, and subsequently "round table" sessions have provided the opportunity for these industrialists to make contact with European industrialists and to discuss terms and joint actions contracts. The feasibility and financing of projects has then been addressed. Finally, before projects have been launched, training sessions have been organized for the entrepreneurs and for their production workers, as well as for the architects and builders who will be using the CEB. Once the enterprise is running, this framework of support and assistance has gone on through the setting up of a "quality programme" (product quality, the quality of houses built, and the elaboration of realistic standards acceptable to all.)
an industrial plant
This type of programme for the encouragement of partnerships, given its current success in the Cameroon and other African countries, will soon be organized in Latin America (Peru, Ecuador, Venezuela, Columbia and Bolivia). It will then be extended to partnership with Eastern countries.
Finally, mention must be made of the fact that the BASIN network is entirely consistent with the spirit of this approach. The various services of the network naturally aim to circulate technical information but also hope to provide an exchange of information between all professionals involved in the production and use of local materials.
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