Enhancing alkali-activated materials with low quality fly ash: A novel mixing approach for robust construction materials

Abstract

It is highly desirable to use industrial waste materials such as fly ash with high impurities as precursors to produce alkali-activated materials (AAMs) and create sustainable construction materials. A novel, simple and efficient mixing method is introduced in this study for producing robust AAMs from precursors with high impurities. The primary precursor utilized for AAM samples was low-quality fly ash with large particle sizes and high levels of impuri-ties such as unburned carbon and sulfur oxides. In the new mixing procedure, the initial step was to dissolve the precursor in sodium hydroxide solution, followed by introducing sodium silicate solution as the final step. To examine the microstructures and phase changes of the precursor, advanced analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Raman spectroscopy (RS) were utilized. Using RS to monitor the dissolution phase was a novel and particularly beneficial technique discovered in this study, as it helped determine the ideal mixing time based on the results. The new mixing procedure has the potential to considerably enhance various properties of AAMs, including fresh and hardened properties, as well as the durability of AAMs.