Characterization of early-age hydration process of cement pastes based on impedance measurement

This paper investigates the hydration process of cement pastes using an isothermal calorimetry, Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis and non-contact impedance measurement (NCIM). The reliability of impedance data from NCIM is checked by classical Kramers-Kronig transformation. Hydration behaviors of pure cement paste in different stages (dissolution, competition and acceleration stages) are interpreted by FTIR, XRD and NCIM. Influences of water to cement ratios, fly ash, slag, silica fume and curing temperature are investigated by compressive strength test and NCIM. It is found that the compressive strength and impedance data have a good linear relationship.