The effect of glass structure on the pozzolanic activity of siliceous fly ashes

ISSN： 0031-9090

Source： Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B, Vol.54, Iss.2, 2013-04, pp. : 89-94

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

The effect of glass structure on the pozzolanic activity of siliceous fly ashes is presented. Two synthetic glasses with compositions similar to those of fly ash were prepared from mixtures of the pure chemical reagents. The mixtures were melted at a high temperature of 1490°C for 1 h and then immediately quenched by water cooling to create the glasses. X-ray diffraction (XRD) and spectroscopic studies in the far-infrared range (FIR) confirmed the amorphous character of the materials. The structure of glasses was characterized by spectroscopy in the mid-infrared range (MIR) and ²⁷Al magic angle spinning-nuclear magnetic resonance (MAS-NMR). The results confirmed the presence of two bridging bonds, Si-O-Si and Si-O-Al, in the glasses. In addition to [SiO₄]^4- and [AlO₄]^5- anions, [AlO₆]^9- octahedral units were also found in the structure of glass. The function of the Al³⁺ ion depends on the aluminium saturation index (ASI), defined as the charge ratio Al₂O₃/(Na₂O+K₂O+2CaO). The greater the ratio of AlO₆/AlO₄, the better pozzolanic activity of glasses as defined by ASTM C379-65T and ASTM C593-06.