Synthesis of Fly Ash-GGBS-Blended Geopolymer Composits

Abstract

Fly ash and blast-furnace slag are well-known industrial by-products and are used to manufacture blended cements and concrete. Fly ash has been used as pozzolanic material to improve the physical, mechanical as well as chemical properties of the cements and concrete, whereas blast-furnace slag cements are characterized by their low heat of hydration and high sulphate and sea water resistance. On the other hand, addition of blast-furnace slag to fly ash may have substantial influence on the strength development of geopolymer binder when cured under ambient temperature condition. This paper presents the compressive strength of geopolymer binders synthesized from Class-F fly ash (FA) blended with ground granulated blast-furnace slag (GGBS) by optimizing the influential parameters. The chemical activation of fly ash–slag mixtures with different concentrations of sodium hydroxide (NaOH) for varying solution to solid ratio has been made. The test results showed that the development of compressive strength is directly concomitant to concentration of NaOH solution. Moreover, as the slag content in the mixture increases, the compressive strength increases. Hence, an inorganic polymer can be synthesized from fly ash–slag mixture by activating with appropriate amount of NaOH which can be used as cementitious material.