COMPARISON OF IR TECHNIQUES FOR THE CHARACTERIZATION OF CONSTRUCTION CEMENT MINERALS AND HYDRATED PRODUCTS

The influence of FT-IR sampling techniques on the characterization of cement systems was investigated. Three FT-IR techniques were used to s tudy tricalcium silicate (C3S), hydrated C3S, calcium hydroxide, and c alcium silicate hydrate (C-S-H). They include transmission spectroscop y (TS), photoacoustic spectroscopy (PAS), and diffuse reflectance infr ared Fourier transform spectroscopy (DRIFTS). The TS technique (using KBr pellets) was the most labor-intensive but was found to give the si mplest spectra with well-defined bands. The PAS technique was found to be the simplest technique but yielded bands at lower wavenumber than TS. DRIFTS was determined to be a good alternative for cement powders since it provided spectra similar to those for the TS technique. DRIFT S required more sample preparation than PAS but less sample preparatio n than the KBr pellet technique.