Abstract
The galeb of Kebili is a sun-dried brick belonging to the construction tradition of the homonymous “oasis city” of southern Tunisia, obtained by mixing water, fired gypsum-rich Sahara sand and palm wood ash. In recent years, great efforts have been made to enhance the features of these construction materials while preserving the traditional production techniques. In order to evaluate possible improvements in the brick’s physical and mechanical properties, both different firing techniques of raw materials and various ash content in the composition, have been considered. Experimental results showed that modifying the traditional method of combustion by firing the sand at a controlled temperature (160 °C) in a standard oven, allows to obtain a galeb brick with improved mechanical and physical properties. Moreover, keeping the traditional method of combustion, mechanical and physical properties may be optimized by adding a controlled amount of raw ash (about 5 %) in the galeb bricks composition.
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Notes
The main mineralogical component is CaSO4·2H2O (calcium sulphate dihydrated).
In 2004, an integrated program aiming to valorize Sahara and Southern Tunisia regions, titled “Study, preservation and valorization of Tunisian Oasis Cities”, has been promoted by the Architecture Faculty of Mediterranea University of Reggio Calabria and the Architecture School of the University of Carthage (Tunisia), and supported by the Italian Ministery of Foreign Affairs.
At T > 250 °C the soluble phase of calcium sulphate anhydrous (CaSO4-α) is transformed into an insoluble phase (CaSO4-β), much less reactive with water.
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Ben Ali, F., Iucolano, F., Liguori, B. et al. Physical and mechanical characterization of sun-dried bricks. A case history: the galeb of Kebili . Mater Struct 49, 159–165 (2016). https://doi.org/10.1617/s11527-014-0483-4
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DOI: https://doi.org/10.1617/s11527-014-0483-4