The application of Raman spectrometry to the investigation of cement: Part II: A micro-Raman study of OPC, slag and fly ash

Various attempts to use Raman spectrometry to analyse the mineral phases in hydrated and unhydrated cement have been made and results were published on pure synthesized mineral phases as early as 1976. Limited investigations were reported in the past three decades on pure mineral cement phases, white cement and ordinary Portland cement (OPC) analysed with visible (VIS) excitation at 514.5 and 632 nm (mainly with normal Raman spectrometry) and near-infrared (NIR) excitation at 1064 nm (mainly Fourier Transform Raman Spectrometry — FT–Raman). Results were distinctly different for VIS and NIR lasers. Newman and co-workers assigned these differences to a fluorescence phenomenon. Previous work on the characterization of secondary cement materials (SCMs) by means of Raman spectrometry is even more limited. This work focused on the characterization of OPC, fly ash and slag, using ultraviolet–visible (UV–VIS), VIS and NIR excitation in micro-Raman spectrometry and the results obtained for OPC and fly ash will be compared with previously published results.