Bird Nest Construction - Lessons for Building with Earth B. SILVA 1 , J. CORREIA 1 , F. NUNES 1 , P. TAVARES 1 , H. VARUM 2 , J. PINTO 1 1 Engineering Department / ECT / CQVR / Chemical Department Trás-os-Montes e Alto Douro University 5001-801 Vila Real PORTUGAL 2 Civil Engineering Department University of Aveiro 3810-193 Aveiro PORTUGAL 1 tiago@utad.pt http://www.utad.pt 2 hvarum@ua.pt http://www.ua.pt Abstract: - The climate changes issue is probable the top priority concern of the governments of the most countries of the world. Rigid and drastic measures have to be taken by all nations in order to reduce the noxious gases emission to the atmosphere. This ambitious goal can be achieved by ruling the energy production, by having a much more sustainable industry and adopting a much more sustainable way of living by all of us. The building industry has also to adapt to these circumstances to make its contribution to achieve the above goal. Focusing on traditional building techniques which require simple technology and use natural and local building materials and, eventually, to adapt them for the present required quality standards may be a step to solve this problem. Half of the world`s population, 3 billion people approximately, on six continents, live or work in buildings constructed by earth based building materials. The fact that earth is natural, abundant and local result in an unexpressive amount of energy spending and noxious gases emission when it is used as a building material and, consequently, makes it undoubtedly much more ecological and economic when compared to the others building materials such as reinforced concrete or steel. In this context, the main objective of this research work is to give a contribution on the earth based building material properties and, in particular, for the development of adequate rehabilitation and strengthening techniques, based upon a biomimetic study focused on the andorinha-dos-beirais nest. A structural numerical model of a nest using a finite element computer analysis program was done in order to understand the structural behavior of this kind of natural structures. In order to identify a possible occurrence of a certain agglutination phenomenon during the building process of the nest by the birds, an experimental identification/characterization study of nest’s material using samples taken in Vila Real area was carried out. The identification of the elementary chemical and the mineralogical compositions of the material were done by the scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and by the X-ray diffraction analysis, respectively. The identification/characterization of the organic composition was done using the colorimetric method, being the protein components detected by the biuret method and the polysaccharides/sugars components by the total sugar method. The identification of the type of polysaccharides/sugars and their amount was done by the anion-exchange chromatography method. In order to verify if the addition of polysaccharides/sugars into the nest’s material results in an improvement of the mechanical properties, in particular, of its compressive strength, mechanical tests were carried out on cubic specimens, The results show that there is a strong possibility of the bird andorinha-dos- beirais adds a certain amount of glucose into the clay material during the building process of the nest, which may increase the quality of this raw material. This result may be easily extrapolated for the building industry by mixing up a certain percentage of glucose obtained by an abundant plant or fruit with the earth resulting in this way in a better performance earth based building material. Key-Words: - Raw materials, Earth construction, Biomimetics, Nest bird, Characterization, Finite element analysis 1 Introduction Half of the world’s population approximately, 3 billion people on six continents, lives or works in buildings constructed of earth [1]. In the third world countries almost half of the existing buildings are made of earth [2].The earth construction is a worldwide heritage that reflects the existing cultural diversity of people [3]. Examples of ancient earth constructions are: the China Wall (2000 B.C.) [4]; and, the Arge Bam city in Iran (500 B.C.) [5]. This impressive earth heritage also reveal that earth construction can have a very sustained durability. At the same time, cutting edge modern earth WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT B. Silva, J. Correia, F. Nunes, P. Tavares, H. Varum, J. Pinto ISSN: 1790-5079 83 Issue 2, Volume 6, February 2010