Proving the role of boron in the structure of fly-ash/borosilicate glass based geopolymers

Abstract A spectroscopic investigation was carried out in order to determine the boron evolution into the structure of fly-ash based geopolymers, integrated with borosilicate glass coming from pharmaceutical waste. Fourier transformed infra-red (FTIR) spectroscopy was used to define the type of bonds after geopolymerization. Various solid-state nuclear magnetic resonance (MAS-NMR) measurements were instrumental to evaluate the extent of network formation in the structure and to compare the type of environments among the geopolymerization products and the source materials. 11 B NMR conducted firstly on a pure borosilicate glass sample and then on a geopolymeric sample evidenced a variation of the chemical shifts of the pattern, proving that boron oxide (B 2 O 3 ) initially dissolved and then took part in polycondensation reactions. FTIR spectroscopy showed the characteristic peaks of a geopolymeric product, also proving that the effectiveness of the reaction was not affected by incorporation of boron.