Effect of alkali concentration on mechanical properties, microstructure, zeta potential and electrical conductivity of thermally cured fly-ash-blast furnace slag based blended geopolymer composites

Abstract

A study has been made on Fly-ash-blast furnace slag blended geopolymer composite. Formation of an alumino silicate hydrate gel in presence of fly ash requires an activator solution of higher pH but formation of calcium silicate hydrate gel in presence of blast furnace slag requires an environment of lower pH. Therefore, an attempt has been made to appreciate the role of alkali concentration to have a high performance Fly-ash-blast furnace slag blended geopolymer composite. The test samples have been subjected to a curing temperature of 60 oC and alkali content has been varied from 4% to 12%, to appreciate the role of alkali concentration which fosters the growth of both type of gels. The reaction products and microstructure have been analyzed by SEM/EDAX, XRD and FTIR analysis. Zeta potential and electrical conductivity values have been also been studied to appreciate the colloidal stability of the blended composite under different alkali concentration.