Geopolymers:: same basic chemistry, different microstructures

The present paper describes the effect of certain working variables on the microstructural evolution of oven-dried, alkali-activated fly ash. The results show that the main reaction product in the activation process (in all the systems studied) is an amorphous aluminosilicate gel with a three-dimensional structure. Nonetheless, the type and concentration of the activator used as well as the natural ageing of the materials and origin of the prime materials were also found to have a substantial impact on microstructural development in the geopolymers synthesised, particularly from the morphological standpoint.