Characterization of Fly Ash on Geopolymer Paste

The effect of loss of ignition, specific gravity, fineness, specific surface area and soluble fly ash to compressive strength of geopolymer paste were studied. Six fly ashes from two different sources and different time of collection were evaluated. Sodium hydroxide and sodium silicate were used as alkali activator. Concentration of sodium hydroxide and mass ratio of sodium hydroxide to sodium silicate were fixed 14M and one respectively. The result indicated that the improvement in compressive strength of geopolymer paste was more influenced by fineness, specific surface area and soluble content of fly ash. Soluble content of fly ash greatly affected the compressive strength of geopolymer paste compare to the compressive strength of cement paste with 20% fly ash replacement.