The geopolymer binders are relative new materials with three-dimensional polymer structures having a preponderant amorphous character compositional similar, natural feldspar. These materials are synthesised by the processing of silico-aluminates materials like fly ashes, granulated blast furnace slag, metakaolinite, with alkaline solutions like hydroxides or silicates. The compositional characteristics and processing peculiarities influence the geopolymers synthesis and microstructure. These factors influence the development of mechanical strengths.

The present paper brings information concerning the microstructural and compositional characteristics of some geopolymers synthesized from fly ash and NaOH solution in different conditions of curing.