Geopolymer binder: A veritable alternative to Portland cement

Abstract

This paper presents the progress made on the research carried out on Geopolymer concrete using available local raw materials. The aim was to find alternative to Ordinary Portland cement(OPC) which has attracted a lot of criticisms due to inherent danger associated with its production. It is established fact that the production of OPC is characterised with high emission of carbon dioxide due to calcination of lime stone and combustion of fossil fuel, coupled with high energy demand associated with its production. This has generated a global concern and call for alternative binder to conventional Portland cement, which will be environmentally friendly. It is on this bases that a new type of binder known as “Geopolymer” was discovered as a suitable substitute to Portland cement which is environmentally friendly. It uses low energy in its production, emits less carbon dioxide and has high mechanical and durability properties which are not found in conventional Portland cement. Moreover, the utilisation of local raw materials like fly ash, blast furnace slag, silica fume etc which are activated with alkali made it veritable alternative building material. Many research scholars used fly ash as the only source material for geopolymer concrete. In this paper, silica fume and kaolin were blended to produce geopolymer concrete and their mechanical properties of were investigated and compared with OPC concrete. The alkali activators used were sodium silicate and sodium hydroxide. Grade 30 OPC concrete designated as PCC in this experiment was designed and used as control. From the result, the compressive strength of geopolymer concrete was higher than OPC concrete. Blending silica fume and kaolin increased the compressive strength. Moreover, the tensile and flexural strengths increased more than the control.