Call edition 2012
A new edition of the Prize of the Belgian Development Cooperation has been launched. This call is open until March 31st, 2011. You can read in the regulations whether you comply with the criteria for participation.
This study relates to civil architecture in Peru, in particular the construction of inexpensive housing in urban areas via the development of a cheap building material based on cement and reinforced by the addition of natural fibres, most of which are locally available. These are cellulose fibres obtained from old paper and natural sisal fibres. As a matrix for the composite material a mix of cement and paper paste is used, the latter contributing to the material’s strength by the introduction of cellulose fibres. The study shows that a proportion of 55% paper paste, 5% chitosan (see further) and the rest cement produces the best mechanical properties.
Natural fibres, however, can biologically degrade – an undesirable side-effect in this context – and swell as a result of water absorption. This must be prevented by the addition of a suitable amount of chitosan. Chitosan has an antibacterial action and is made from chitin, which is found in the exoskeletons of crabs and shrimps and is therefore also locally available.
The addition of sisal as a supplementary natural fibre does not increase the strength of the matrix – which is attributed to poor adherence with the matrix – but does ensure that the entire material will not disintegrate if cracks occur. Only a small fraction of sisal fibre can be added to the material, however, otherwise its strength is reduced again.
The basic material satisfies the mechanical demands of ASTM* norms for light concrete materials. Biodegradation tests have shown that an addition of 3% chitosan significantly reduces the formation of mould. Varnishes containing chitosan that have the same protective effect have also been developed and tested. Although further research is still needed, an important step has been taken here towards the development of a construction material based on cheap available building materials. In consequence, the project also has great relevance to development.
*ASTM: American Society for Testing and Materials
Report : Prof. Y. Houbaert, Department of Metallurgy and Materials Science, Faculty of Engineering, Universiteit Gent, Belgium