Influence of Sand to Binder Ratio on Properties of Geopolymer Mortar Containing Portland Cement

Abstract

This article reports the influence of sand to binder ratio (S/B) on selected properties of geopolymer mortar containing Portland cement. Fly ash (FA) was replaced by Portland cement (PC) at the dosages of0%, 5%, 10%, and 15% at various sand to binder ratios of 1.00, 1.25 and 1.50. The solutions which were used as a liquid alkali solutions were sodium silicate (Na2SiO3) and 6-molar sodium hydroxide (NaOH) solutions. The Na2SiO3/NaOH ratio of 2.0, liquid/binder ratio of 0.60 and ambient curing temperature were
used in all cases. The results showed that the setting time of geopolymer mortar tended to decrease with an increase in the PC replacement. While the S/B ratio increased, the setting time of geopolymer mortar tended to increase. The compressive and flexural strengths of geopolymer mortar obviously increase with an increase in the PC replacement. S/B ratio of 1.25 resulted in the highest compressive strength of the geopolymer mortar, while the S/B ratio of 1.50 resulted in the highest flexural strength of the geopolymer mortar.