A feasibility study on using different techniques (Raman spectroscopy, FT-IR, DSC, XRD and compressive strength test) in order characterize geopolymers has been done to understand how to better employ fly ash as a supplementary material in the production of concrete. Fly ash, Class F, was polymerized using potassium hydroxide as an activator and potassium silicate solution; the samples were done with a KOH concentration of 4 M and 6M, and changing the liquid and solids ratio between 0,4; 0,5; 0,6 and 0,7. Preprocessing was used on the raw spectra obtained using Raman spectroscopy. IR spectroscopy was used as a complementary technique for Raman spectroscopy The DSC analysis were performed using nitrogen atmosphere, with a heating rate of 20 °C/min between 25 °C and 550 °C. The phases of geopolymer and cement materials were studied with XRD. Compressive strength was done on 25 mm diameter and 50 mm height samples using the instructions of ASTM C39/C39M.