Effect of ratio between Na2SiO3 and NaOH solutions and curing temperature on the early age properties of geopolymer mortar

Abstract

Geopolymer is the new generation civil engineering material and it is replacing the conventional cement in constructional activities. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions were used as alkaline activators to develop the geopolymer mortar in this investigation. The effect of the ratio of Na2SiO3 / NaOH (SS/SH) in the activator solution on the fresh and hardened mortar strength were studied and reported in this paper. Thermal curing was followed in most of the previous research findings and it has various limitations for cast-in-situ applications. Further, the ambient temperature curing method was considered in this study to overcome the limitations and the results were compared and presented. The control geopolymer mortar was developed with class F type fly-ash (FA). Ground granulated blast furnace slag (GGBS) and corn cob ash (CCA) were substituted as FA replacing basic materials. The experimental results had shown that the addition of GGBS and CCA reduced the flow value and setting time of fresh geopolymer mortar and increasing the compressive strength of geopolymer mortar. The experimental outcomes showed that the compressive strength of geopolymer mortar was increased due to increasing the ratio SS/SH. While considering ambient curing environment instead of thermal curing, the strength development pattern was modified and compressive strength was decreased in all the rest period.