Sulphate resistance of slag blended fly ash based geopolymer concrete

Inclusion of ground granulated blast furnace slag (GGBFS) together with fly-ash can have significant effects on the development of strength and durability properties of geopolymer concrete when cured at normal temperature. To study the effect of GGBFS in fly ash based geopolymer concrete, four different geopolymer mixtures suitable for curing at ambient temperature and an ordinary Portland cement concrete were used. A combination of sodium hydroxide and sodium silicate alkaline activator was used to react with fly ash and GGBFS. GGBFS was added as 10% and 20% of the total binder. The durability of GGBFS blended fly ash based geopolymer concrete in sulphate environment was tested. The changes in weight, length and compressive strength due to exposure in sodium sulphate solution for different periods of time were determined. The test results demonstrate that GGBFS blended fly ash based geopolymer concrete cured at normal temperature has good resistance to sulphate attack. In general, inclusion of GGBFS with fly ash in geopolymer concrete improved strength and performed satisfactorily in sulphate environment when cured in ambient temperature