Design Method for Optimizing Geopolymer Concrete Proportions Utilising Entirely Steel Slag Aggregates

Abstract

Fly ash and steel slag, which are byproducts from thermal power and steel plants respectively, have been used to manufacture geopolymer concrete (GPC). When combined, fly ash-based GPC using steel slag aggregate (GPCs) is effective in solving environmental concerns caused by the excess of byproducts. However, compared to Portland cement concrete (PCC), GPC is a newer material, and its mix design method to target a specified compressive strength has not been defined. To help make the GPCs mix design process more efficient, this paper discusses a statistical model that can be used to estimate the compressive strength of GPCs mixtures with 100 percent steel slag aggregates. The model was developed based on an experimental design in which the three variables were varied as follows: (1) the sodium solution (NaOH) concentration was varied between 10 and 14M, (2) the mass ratio of alkaline activation solution to fly ash (AAS/FA) was changed from 0.4 to 0.5, and (3) and the mass ratio of sodium silicate (Na2SiO3) to sodium hydroxide solution (SS/SH) was varied from 2 to 3. Results obtained in this study show that the model can reasonably estimate the compressive strength of GPCs mixtures based on the three variables, so it is recommended for use in GPCs mix design in the future.