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 study tricalcium silicate (C3S), hydrated C3S, calcium hydroxide, and calcium silicate hydrate (C-S-H). They include transmission spectroscopy (TS), photoacoustic spectroscopy (PAS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The TS technique (using KBr pellets) was the most labor-intensive but was found to give the simplest 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. DRIFTS required more sample preparation than PAS but less sample preparation than the KBr pellet technique.