In the present work, a study of the effect of different solid/liquid (S/L) ratio on fly ash geopolymer was investigated. The geopolymer were prepared by mixing fly ash with alkali activator (a mixture of sodium hydroxide and sodium silicate). The S/L ratios were used 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5 with fixed sodium silicate/sodium hydroxide ratio of 2.5 and 8M of sodium hydroxide. The geopolymers were cured at room temperature (29°C) for 24 hours and at 60°C for another 24 hours. The testing and analysis of the fly ash geopolymers were performed after 28 days. The geopolymer showed highest compressive strength (37.6MPa) with 3.0 of S/L ratio, further decreased in compressive strength (2.7MPa) was observed at 3.5.
