Effect of nano silica and steel fiber on fresh state and mechanical properties of self-compacting geopolymer concrete

This thesis investigates the properties of the self-compacting geopolymer concrete (SCGC) in both the fresh and hardened state under the combined addition of nano-silica (NS) and steel fiber (SF). Nine mixtures of SCGC containing different percentages of NS (0 %, 1 % and 2 %), and different percentages of SF (0 %, 0.5 % and 1 %) were prepared for the study. SCGC were prepared using 50 % fly ash (FA) and 50% ground granulated blast furnace slag (GGBFS) with a constant alkaline activator to binder ratio of 0.5. A blend of sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) with a ratio of 2.5 has been chosen as an alkaline activator. The Fresh state and hardened concrete tests including slump, flowability, workability, compressive strength, bonding strength, and flexural strength were carried out in the study. Experimental results were examined in detail to determine the impact of important factors on the mechanical performance of SCGC. Furthermore, correlations between the experimental data were evaluated to explore the relationships between the fresh and hardened state properties of geopolymer concretes. Experimental results showed that the combined use of NS and SF affected the fresh state properties adversely, while it improved the bond strength and flexural performance of the SCGC specimens significantly. In addition, the effect of NS was predominant regarding fresh state properties and compressive strength, while the effect of SF was superior regarding flexural and bonding strength.