Effect of Alkali-Activator to Bottom Ash Ratio on the Undrained Shear Strength of Bottom Ash based Geopolymer

Abstract

Coal ash is generated as a raw product during combustion in thermal power plants. These industrial wastes include fly ash and bottom ash, which has been deemed as a source materials for geopolymer. Bottom ash is used in soil columns for stabilizing foundation soil. In the present study bottom ash from Tanjung bin power station was used as a substitute materials for making geopolymers. The effect of alkali activator to bottom ash ratio on the undrained shear strength of bottom ash based geopolymer was studied. The molarity of sodium silicate solution was kept as 14, Na2SiO3/NaOH of ratio 2.5, mass ratio of alkali activator to bottom ash 0.40, 0.50 and 0.60, and steam curing at 65°C were attempted for the samples. The experimental results of UU triaxial test indicate that alkali-activator to bottom ash ratio of 0.50 gives higher undrained shear strength.