Characterisation and life-cycle assessment of alkali-activated concrete using industrial wastes

Conventional cement concrete has surfaced as a major construction material with considerable global warming potential. Alternatively, a fly ash (FA) ground-granulated blast furnace slag (GGBS)-based alkali-activated concrete is introduced to attain the goal of net zero emission and reduce the environmental impacts. In this study fixed proportions of concrete mixes matching with a designated strength of plain cement concrete mix have been determined. In addition to this, an ambient curing condition has been integrated that will be helpful for practical implementation in large-scale construction. Sodium silicate and sodium hydroxide were used as alkaline activator solutions to activate the FA and GGBS. The alkali activator reciprocity, i.e. Na2SiO3/NaOH (NS/NH), was set at 2.5. For various combinations of FA and GGBS, the main parameters considered in this study were molarity of sodium hydroxide and alkaline solution/binder ratio. The variation implemented in this experimentation includes: proportions of FA and GGBS (80-20, 75-25, 70-30, 65-35, 60-40, 55-45 and 50-50) and molarity of NaOH (10, 12, 14 M). Results concluded that the FA-GGBS-based alkali-activated concrete exhibits better performance as compared to conventional concrete. Furthermore, X-ray diffraction, Fourier transform infrared spectrography, scanning electron microscopy and energy-dispersive X-ray are carried out to investigate the behaviour of microstructure of GPC. Life-cycle impact category values have also been estimated considering all possible construction scenarios.