Abstract
Tunisian and Portuguese smectitic clays are under study to assess their potentialities to be used as naturalraw materials for the production of Light Weight Aggregates which have an important function in civilconstruction work. Several smectitic clay deposits from the meridional Atlas domain (Tunisia) and fromthe Meso-Cenozoic Lusitanian Basin (Portugal) were studied for this purpose. Characterization of theseclays includes mineralogical and chemical analysis, dosage of total organic carbon, grain size analysis andthermal analysis. Small balls (1 to 1.5cm in diameter) were prepared with these clays in the plastic stateand were submitted to the firing temperatures ranging from 1050up to 1180°C, during time intervalsranging from 5 to 15min. Special additives like motor oil, phosphate residues and sand, in differentproportions, were mixed with the smectitic clays in order to obtain better expansion. The followingproperties were determined on the bloated balls: apparent density, mechanical resistance corresponding tothe rupture under compression point and water absorption. The bloated balls showed appreciableproperties. Each additive has positive effects but in dependent on the original clay material. The resultswere comparatively appraised not only between Tunisian and Portuguese clays but also with commercialproducts.
