Geopolymerization index of fly ash geopolymers

Samples of pozzolanic and geopolymer binders prepared using pozzolanic reaction between lime and fly ash and fly ash activation were used for investigation of the structure of these materials and its relations to the Raman spectra. Binding phase development of these materials and its possible relation to silicate glasses was investigated using Raman spectroscopy. Additionally, micro Raman spectroscopy, X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were used in order to analyze evolvement of the binding phase in the materials and its dominant structure. The obtained results suggest glass-like behavior of the investigated samples and introduce new perspective in research of geopolymerization mechanism. Although solid state NMR is a widely accepted method for determination of SiO4 tetrahedra polymerization type present in geopolymers, the obtained results suggest Raman spectroscopy as an equally useful or event more suitable method. The obtained data show strong possibility to use Raman spectroscopy in order to determine the degree of conversion of the starting materials to the wanted geopolymer product. Based on the obtained results, the “Geopolymerization Index” was introduced as a new concept, and its calculation using Raman spectra is proposed.