Geopolymer Concrete Optimization Investigating the Influence of Pozzolanic Minerals and Slag Binder Combination on Workability and Mechanical Strength Characteristics at Ambient Temperature

Abstract

Due to its environmental benefits and promise as a long-term alternative to standard concrete construction, geopolymer concrete (GPC), also known as earth friendly concrete, has been the subject of continuous study. Detailed studies focusing on the influence of all design mix elements on the fresh and strong properties of GPC, on the other hand, are still absent. In terms of field use, GPC is still a relatively new material that has yet to attract general acceptance as a building material. As a result, in order to push this relatively new material technology to field and site applications, extensive research must be done to acquire more reliable information. The goal of this research is to provide a comprehensive assessment of the parameters influencing the fresh and hardened properties of ambient cured fly ash and slag-based geopolymer concrete (FS-GPC). To manufacture ambient cured FS-GPC, manufacturing by-products such as fly ash from thermal power plants and ground granulated blast furnace slag from steel firms were employed. A series of research were conducted to investigate the effect of various the variables on the fresh and mechanical properties of FS-GPC, such as slag content (10, 20, 30, and 50%), the volume of Alkaline Activator Solution (AAS) (35 and 40%), Sodium Silicate (SS) to Sodium Hydroxide (SH) ratio (SS/SH = 2.0, 2.5, and 3.0), the concentration of sodium hydroxide (10 M, 12 M, and 14 M), and incorporating extra water. The slump cone experiment was used to evaluate the workability of the new FS-GPC mixtures. The mechanical characteristics of the mixes were evaluated using compressive strength, split tensile strength, flexure strength, and static modulus tests. The results demonstrated that increasing the slag concentration, NaOH solution molarity, and SS/SH ratio considerably affects the workability of FS-GPC. By raising the molarity of the NaOH solution and slag concentration while decreasing the AAS content from 40% to 35%, compressive strength was enhanced. The effect of the SS/SH ratio on the mechanical properties of FS-GPC, on the other hand, varies. The incorporation of more water in order to enhance the workability of the GPC matrix reduced compressive strength. Prior study equations for predicting tensile and flexural strength and elastic modulus of FS-GPC blends were also validated. Empirical calculations for estimating the splitting tensile strength, flexural strength, and elastic modulus of ambient cured FS-GPC are proposed according to the results of this study's experiments. Acceptable FS-GPC blends in terms of workability and mechanical qualities have been suggested as well for use in field applications.