Strength of geopolymer paste using a ternary blend of fly ash GGBFS and silica fume under ambient conditions

Abstract

In this paper, compressive strength (CS) of geopolymer paste has been studied under ambient conditions using locally available Class C fly ash, GGBFS and silica fume and a combination alkali activator, namely: NaOH and Na2SiO3. Two approaches were used for mix proportioning and 60 mixes of the paste were proportioned. It is found that all the mixes proportioned were workable and no adverse effects were observed within 30 minutes of mixing. It is found that the ‘minimum voids’ approach along with a constant fly ash – to – activator ratio (FA/AA) is the best approach for the design of geopolymer mixes, rather than a constant water-to-solid ratio (w/s). Further, the role of GGBFS and SF on the CS of the paste has also been highlighted.