Sedimentary Clays as Geopolymer Precursor

International audienceThis work aims to study the feasibility of making a geopolymer cement based on dredged sediments, from the Fergoug dam (Algeria) and to evaluate their construction potential particularly interesting in the field of special cementitious materials. These sediments due to their mineralogical composition as aluminosilicates; are materials that can be used after heat treatment. The objective of this study which is part of a long research whose is to contribute to the valorization of these sediments of dredging in the formulation of new concretes by complete substitution of cement. Sedimentary clays were characterized before and after calcination by X-ray diffraction, ATG/ATD, spectroscopy (FTIR) and XRF analysis. The calcination was carried out on the raw material sieved at 80 mu m for a temperature of 750 degrees C, for 3, 4 and 5 hours (calcinations times). The reactivity of the calcined products was measured using isothermal calorimetric analysis (DSC) on pastes prepared by mixing an alkaline solution of sodium hydroxide (NaOH) 8 M in an amount allowing to have a Na / Al ratio close to 1 (11). Also, cubic mortar samples were prepared with a ratio L / S 0.8, sealed and cured for 24 hours at 60 degrees C and then at room temperature until the day they were submited to mechanical testing. to check the extent of geopolymerization. The results obtained allowed to optimize the calcination time of 5 hours for a better reactivity of these sediments, and a concentration of 8M of sodium hydroxide and more suitable to have the best mechanical performances