Geopolymetric binder produced with fly ash and sodium hydroxide

Geopolymeric binders are an alternative material to Portland cement that it are obtained by fly ash polycondensation in an alkaline medium, as long as criteria for selection of precursor materials, mixing parameters and curing regime are observed. By employing ground fly ash and a sodium hydroxide solution, the effect on flexural and compressive strength of prismatic specimens was evaluated through changing solution concentration (8 M, 12 M and 16 M), fly ash - alkaline solution ratio by mass (0.50, 0.55, 0.60, 0.65, 0.70), curing regime (in oven or moist chamber) and age (1, 3 or 7 days) according to the aim of each evaluation. The findings of this study were that a second thermal curing may be dismissed and strength values remained stable over time. In addition, the investigation showed a strong effect between mixing parameters, since strength was improved by increasing the molar concentration and reducing the materials mass ratio.