The Study of Disorder in Amorphous Silica, Alkali-Silica Reaction Gel and Fly Ash

Significant progress was achieved with the application of Rietveld method to characterize the crystalline, and nanocrystalline phases in portland cement concrete. However, to obtain detailed information on the amorphous phases present in concrete, it is necessary to analyze the total scattering data. The pair distribution function (PDF) method, that takes the Sine Fourier transform of the measured structure factor over a wide momentum transfer range, has been successfully utilized in the study of liquids and amorphous solids. The method provides a direct measure of the probability of finding an atom surrounding a central atom at a radial distance away. The obtained experimental characteristic distances can be used to validate the predictions by the theoretical models, such as, molecular dynamics simulations. This research focuses on obtained results of PDF analysis on silica fume, rice husk ash, fly ash, alkali-silica reaction gel, and opals