The Performance of Alkali-Activated Self-Compacting Concrete with and without Nano-Alumina

The environmental pollution crisis has infiltrated all aspects of life, making it hard to avoid the hazards. To address this, it is essential to recycle industrial waste through green concrete technology, such as ground-granulated blast furnace slag (S), silica fume, and fly ash (FA). In this study, the effect of nano-alumina (NA) on the fresh and hardened stag of fly ash and/or slag-based alkali-activated self-compacting concrete (A-ASCC) cured in an ambient environment was investigated. Three different types of binders were used: 100% slag, 50% slag and 50% fly ash, and 100% fly ash. Four ratios of nano-alumina (0%, 0.5%, 1%, and 1.5%) were used as partial replacements for binder materials. The fresh characteristics of A-ASCC were evaluated by indicating the slump flow, T50 value, V-funnel, and L-Box tests. The mechanical properties of A-ASCC were evaluated by measuring the compressive strength, flexural tensile strength, and splitting tensile strength test values to assess the qualities of the hardened state. Scanning electron microscopy (SEM) was also used to clarify the microstructure of the A-ASCC specimens. Regardless of the binder materials used, the addition of NA has a negative effect on fresh state performance. The mechanical performance of alkali-activated A-ASCC was significantly improved by the incorporation of NA. The incorporation of NA with 50% slag and 50% fly ash showed better properties than other binder materials. However, the highest flexural and compressive strengths were achieved with 1% NA and 100% FA, and the maximum splitting tensile strength was achieved with 1.5% NA. Furthermore, using NA significantly increases the A-ASCC setting time and may be used to produce A-ASCC in an ambient environment.