Comparative study on the behaviour of GPC using silica fume and fly ash with GGBS exposed to elevated temperature and ambient curing conditions

Abstract

Ordinary Portland cement produces carbon dioxide emissions that impact human health by displacing oxygen in the atmosphere. To reduce the CO2 emissions the Geopolymer concrete (GPC) is the alternative and it is environmentally friendly. In this investigation Silica fume was chosen as the basic material to be activated by the geopolimerization process to be the concrete binder, to totally replace the use of Portland cement. The binder is the only difference to the ordinary Portland cement concrete. To activate the rich Silicon content in Silica Fume, a combination of sodium hydroxide solution and sodium silicate solution was used. The manufacturing process comprises of material preparation, mixing, placing, compaction and curing are reported. Naphthalene based super plasticizer was found to be useful to improve the workability of fresh silica fume based geopolymer concrete, as well as the addition of extra water. The main parameters affecting the compressive strength of hardened silica fume-based geopolymer concrete are the curing temperature and curing time, the molar H2O-to-Na2O ratio, and its mixing time. In addition, Ground Granulated Blast furnace Slag (GGBS) is blended with fly ash in various proportions (20% & 40%) at ambient temperature conditions to produce the geopolymer concrete and the mechanical properties are investigated for the same. The compressive strength test results show that the GGBS based geopolymer concrete (GGPC) gives higher strength at 90 days.