Dynamic behavior of hydration water in calcium-silicate- hydrate gel: A quasielastic neutron scattering

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. The translational dynamics of hydration water confined in calcium-silicate-hydrate (C-S-H) gel was studied by quasielastic neutron scattering spectroscopy in the temperature range from 280 to 230 K. The stretch exponent β, the self-diffusion constant D, the average translational relaxation time τ , and the temperature dependence of confinement radius α extracted from the elastic fraction of immobile water molecules p(Q) were obtained from the analyses of the low-Q spectra according to the relaxing cage model. Measurements were made using C-S-H of three different water contents, 10%, 17%, and 30%. Among the three samples of C-S-H gel with different water contents, the values of β decrease with increasing water contents, while α increases. The values of D and τ are insensitive to temperature for the two lower water contents, as opposed to the 30% case where a slight variation is observed. The trend for violation of the Stokes-Einstein relation is only visible in the case of 30% water content.