Effect of Alkali Concentration on Physico-Chemical Properties of Geopolymer Cement Pastes

Abstract

Geopolymer is regarded as an encouraging sustainable and environmentally favorable material substitute to Portland cement in construction applications. Portland cement generation increments worldwide greenhouse gas emissions outflows through the calcination of clinker in hydrocarbon warmed heaters. Generally, a decrease in cement utilization has been accomplished by the utilization of industrial by-products, for example, fly ash (FA), and ground granulated blast furnace slag (GGBFS) as partial or complete replacement materials to Portland cement in concrete. Various mixes are prepared using different liquid/solid ratio (L/S) by weight. Sodium hydroxide pellets (SH) with commercial sodium silicate liquid (SSL) are used as activator that is dissolved in the mixing water. After complete mixing, the resultant pastes are molded into specimens using one-inch cubic moulds then cured under relative humidity 100% for 24 hours. The specimens are removed from the moulds and cured under relative humidity 100% for different time intervals, namely; 2, 7, 28, 56, and 90 days. Some cubes are immersed (after 28 days curing under relative humidity 100%) in 5% MgSO4 solution for different time intervals up to 90 days.