Properties of blast furnace slag geopolymer concrete

Cement being the most consumed commodity after water contributes about 8% CO2 to the total amount of CO2 emitted. Therefore, alternate binders are being explored to make concrete production more sustainable. Geopolymer an inorganic polymer is being projected as one of the potential alternatives. However, most of the published literature recommend the use of highly concentrated alkali hydroxides of sodium or Potassium as alkali activator or a combination of alkali hydroxide with silicates for geopolymer synthesis, which are unsafe for workers. Furthermore, heat curing regimes of 24 to 120 h at temperature ranging 60 to 85 °C are also recommended. However, heat curing of structural components in a building is not possible in most of the in-situ construction projects, except for the production of prefabricated structural components. Furthermore, the silica and alumina rich wastes are preferred choice as the precursor for geopolymer synthesis. Therefore, an experimental study is carried out to produce blast furnace slag based geopolymer concrete using sodium silicate as the alkali solution. The geopolymer concrete was cured for 7, 14 and 28 days at ambient temperature to assess the mechanical properties of the developed concrete. The results of compressive and flexural strength test indicate the possibility of making ambient cured geopolymer concrete using sodium silicate and granulated blast furnace slag for structural application.