Dielectric study on the hydration process of cement paste

Abstract

The results obtained from the dielectric measurements on the hydration process of cement paste are summarized as follows. 1. In the high frequency loss measurement, the tanδ of Ca3SiO5 showed a large value in the beginning and then decreased gradually with the curing age. It seems to be due to the decrease of the ions which contributes to the electric conductivity by the micelle formation and the fixation of ions with the progress of the hydration. 2. In Ca2SiO4, the tanδ increases with the increase in the curing age and then decreases gradually after passing through the broad peak. Compared with the electric conductivity curve at low frequency, it is considered that not only the loss (σ term) due to the electric conductivity but also the loss (e″ term) due to the dielectric polarization of the quasi-structural group such as the ionic micelle formation and the ion adsorbed layer contribute to the high frequency loss of Ca2SiO4. 3. In cement paste, the tanδ appears to be the sum of the tanδ of Ca2SiO4 and Ca3SiO5. In this case, the setting time of cement paste comes about on the tanδ curve. 4. The results obtained by the electric conductivity measurements seem to support the above conclusion. 5. The results obtained in the present study showed the similar tendency to those obtained in the previous nuclear magnetic resonance study.