The implementation of geopolymers materials from Moroccan clay, within the framework of the valorization of the local natural resources

The feasibility of geopolymers from two local Moroccan clays was performed at room temperature, using calcined clay with potassium hydroxide solution as alkaline medium and Potassium silicate solution. Several compositions with different fraction have been prepared up to obtain those with a homogeneous appearance and well consolidated. Used clays have been characterized for their possible use in the synthesis of geopolymer. The combination of the results of different analysis methods; X-ray fluorescence (XRF), X-ray diffraction (XRD), infra-red spectroscopy (FTIR), thermal analysis (DTA-TG), particle size distribution (PSD), specific surface area (BET) and Solid State MASNMR of 29Si and 27Al allowed to establish the chemical and mineralogical compositions of the used clays. The chemical analysis showed a dominance of silica SiO2 and alumina Al2O3. It demonstrated that the main clay minerals in these samples were kaolinite chlorite and illite with the presence of other minerals. These clays contain two kind of populations; mono-modal and bi-modal with different specific surface area and different behaviors on the thermal analysis depending on their composition. The clay rich kaolinite was thermally treated at 700°C in order to convert it into amorphous metakaolin which is a more reactive precursor for geopolymer synthesis, and then it was characterized by XRD, FTIR and NMR. The calcined clays were tested as potential aluminosilicate sources for the synthesis of geopolymer. The reactions of geopolymerization and the structural evolution of the formed geopolymers were investigated using FTIR spectroscopy.