Saturday, November 24, 2007

Promotion of Interlocking soil/cement bricks for affordable construction

Promotion of Interlocking soil/cement bricks for affordable construction
By S. Asman (Chief Scientific Officer )

Shelter is one of the basic necessities for decent human life and this is why the Tanzania government persistently sensitizes and encourages its citizens to have good habitat both in urban as well as rural areas. Over 80% of the populations live in rural areas where housing construction is mostly done using soil and timber. 

The traditional way of housing construction in most parts of the country is to use mud bricks and poles for the walls and poles and grass for the roof. Responding to the government call for better housing, most people have resorted to building their houses using burnt bricks. Unfortunately the process of making burnt entails an extensive use of fuel wood which substantially contribute to the decline of the forests. Some areas are completely without trees because of brick making activities for housing  and other activities and as such other means for the construction of affordable modern housing have to be made. The development of an inter locking bricks press therefore offers  one of the best options for the construction of affordable shelters in rural, and urban centres like areas especially where fuel wood for making burnt bricks are  either scarce or no longer available.

The Interlocking brick press
The Institute of Production Innovation (IPI) of the University of Dar es Salaam and the Building Research Unit for more than a decade now have been involved in the development of equipment for building materials. One of the recently developed equipment now in the market is the Interlocking Brick Press. The locally developed press is based on the working principles of a press   machine developed in 1956 by Raul Ramirez at the Inter American Housing Centre
 

 . The press is made entirely of steel and consists of a mould box with a cover onto which a toggle lever is rolled. Compaction is achieved manually by impacting the mould contents (i.e a damp mixture  of crush dust and cement) with the mould cover. The weight of the cover and the force applied by the operator are sufficient to achieve brick strength required by the Building industry. Depending on the setting of the mould the machine can produce three different sizes of the brick: a whole brick, half brick, or three quarters of a brick. The three sizes  are necessary during the construction. The machine is easy to operate; one person can operate the machine so long as it is firmly secured to the ground. Soil, cement and water are the major components for the production of the inter locking bricks, and using the recommended mixture or cement and soil, one bag of Cement (50 kg) can produce 150 interlocking bricks . Whereas for the same amount of cement one can get 25 concrete blocks  of size 6� x9� x18�.

The interlocking soil/cement bricks have a variety of advantages: 

        They don�t require mortar in between the bricks during construction

        The hollow portions allow insertion of certain fixtures or conduits without having to do extra work on the building structure.

        They don�t need fire treatment and therefore ease the fast depletion of the forest cover.

        They need less water for their production and treatment compared with  the production of other bricks.

        They use very small amount of cement per brick 

Popularisation of the Interlocking bricks 

Both developers of the interlocking brick press, the IPI and the BRU are engaged in the popularization of the new technology. However in view of the potential environmental impact that can be obtained by an extensive use of the new technology, the Centre for the Development and Transfer of Technology(CDTT) has endeavored to join  IPI and BRU, and speed up  the popularization of the technology to individuals, public as well as private institutions in Tanzania. So far some individual and some private institutions have successfully bee sensitized and the big plan is to reach a much larger segment of the population.   

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