LAUSR

Abstract The structural evolution of geopolymers obtained by the alkaline activation of a natural pozzolan composed by a mixture of feldspars (albite and anorthite), calcite and quartz has been followed up to 28 days. The geopolymers have been synthesized using a sodium silicate solution as an activator with an activator/pozzolan volume ratio =0.6, and curing at room temperature or at 40 °C. The reaction has been followed by isothermal calorimetry and the structural evolution has been followed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). The results show that the phases of albite and anorthite dissolve and that a gel is produced, which is identified by an increment of an amorphous halo observed in the XRD pattern at