Multinuclear MAS NMR Characterization of Fly-Ash-Based Advanced Sodium Aluminosilicate Geopolymer: Exploring Solid-State Reactions

摘要

Advanced geopolymerization includes concept of just addition of water to ready mixture of dry precursor powder. For exploring the coordination environments of binary glass systems, this work presents multinuclear MAS NMR analysis of advanced geopolymer produced by solid state mechanochemical co-grinding of raw materials. The crystalline and amorphous phases of advanced geopolymer were already characterized with XRD in our previous study. This study focus on multinuclear (29Si, 27Al and 23Na) MAS NMR analysis for exploring the coordination environments of Si/Al/Na nuclei in advanced geopolymer. 29Si, 27Al and 23Na MAS NMR spectra of fly ash, advanced geopolymeric precursor material and advanced geopolymer are qualitatively estimated which enables an understanding of insertion of Al in silicate network ensuing solid state reactions during mechanochemical co-grinding process. By combining the NMR interpretations, it can be suitably said that mechanochemical co-grinding is a feasible way to induce local defects in amorphous Si/Al content which lead to variation in bond angles and variations in Si/Al constellations. Results may be very useful to understand framework connectivity, chemistry and behavior of advanced geopolymers produced by solid state route and the developed advanced geopolymer finds its potential application as "ready to use" cementitious material for large scale commercialization.