中国物理B ›› 2016, Vol. 25 ›› Issue (10): 106401-106401.doi: 10.1088/1674-1056/25/10/106401

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

Dynamic behaviors of water contained in calcium—silicate—hydrate gel at different temperatures studied by quasi-elastic neutron scattering spectroscopy

Zhou Yi(易洲), Pei-Na Deng(邓沛娜), Li-Li Zhang(张丽丽), Hua Li(李华)   

  1. Department of Physics, Jinan University, Guangzhou 510632, China
  • 收稿日期:2016-04-07 修回日期:2016-06-27 出版日期:2016-10-05 发布日期:2016-10-05
  • 通讯作者: Hua Li E-mail:tlihua@jnu.edu.cn

Dynamic behaviors of water contained in calcium—silicate—hydrate gel at different temperatures studied by quasi-elastic neutron scattering spectroscopy

Zhou Yi(易洲), Pei-Na Deng(邓沛娜), Li-Li Zhang(张丽丽), Hua Li(李华)   

  1. Department of Physics, Jinan University, Guangzhou 510632, China
  • Received:2016-04-07 Revised:2016-06-27 Online:2016-10-05 Published:2016-10-05
  • Contact: Hua Li E-mail:tlihua@jnu.edu.cn

摘要: The dynamic behaviors of water contained in calcium-silicate-hydrate (C-S-H) gel with different water content values from 10% to 30% (by weight), are studied by using an empirical diffusion model (EDM) to analyze the experimental data of quasi-elastic neutron scattering (QENS) spectra at measured temperatures ranging from 230 K to 280 K. In the study, the experimental QENS spectra with the whole Q-range are considered. Several important parameters including the bound/immobile water elastic coefficient A, the bound water index BWI, the Lorentzian with a half-width at half-maximum (HWHM) Γ1(Q) and Γ2(Q), the self-diffusion coefficients Dt1 and Dt2 of water molecules, the average residence times τ01 and τ02, and the proton mean squared displacement (MSD) <u2> are obtained. The results show that the QENS spectra can be fitted very well not only for small Q ( ≤ 1 Å-1) but also for large Q. The bound/immobile water fraction in a C-S-H gel sample can be shown by the fitted BWI. The distinction between bound/immobile and mobile water, which includes confined water and ultra-confined water, can be seen by the fitted MSD. All the MSD tend to be the smallest value below 0.25 Å2 (the MSD of bound/immobile water) as the Q increases to 1.9 Å-1, no matter what the temperature and water content are. Furthermore, by the abrupt changes of the fitted values of Dt1, τ01, and Γ1(Q), a crossover temperature at 250 K, namely the liquid-to-crystal-like transition temperature, can be identified for confined water in large gel pores (LGPs) and/or small gel pores (SGPs) contained in the C-S-H gel sample with 30% water content.

关键词: dynamics of water, quasi-elastic neutron scattering spectra, empirical diffusion model, C-S-H gel pastes

Abstract: The dynamic behaviors of water contained in calcium-silicate-hydrate (C-S-H) gel with different water content values from 10% to 30% (by weight), are studied by using an empirical diffusion model (EDM) to analyze the experimental data of quasi-elastic neutron scattering (QENS) spectra at measured temperatures ranging from 230 K to 280 K. In the study, the experimental QENS spectra with the whole Q-range are considered. Several important parameters including the bound/immobile water elastic coefficient A, the bound water index BWI, the Lorentzian with a half-width at half-maximum (HWHM) Γ1(Q) and Γ2(Q), the self-diffusion coefficients Dt1 and Dt2 of water molecules, the average residence times τ01 and τ02, and the proton mean squared displacement (MSD) <u2> are obtained. The results show that the QENS spectra can be fitted very well not only for small Q ( ≤ 1 Å-1) but also for large Q. The bound/immobile water fraction in a C-S-H gel sample can be shown by the fitted BWI. The distinction between bound/immobile and mobile water, which includes confined water and ultra-confined water, can be seen by the fitted MSD. All the MSD tend to be the smallest value below 0.25 Å2 (the MSD of bound/immobile water) as the Q increases to 1.9 Å-1, no matter what the temperature and water content are. Furthermore, by the abrupt changes of the fitted values of Dt1, τ01, and Γ1(Q), a crossover temperature at 250 K, namely the liquid-to-crystal-like transition temperature, can be identified for confined water in large gel pores (LGPs) and/or small gel pores (SGPs) contained in the C-S-H gel sample with 30% water content.

Key words: dynamics of water, quasi-elastic neutron scattering spectra, empirical diffusion model, C-S-H gel pastes

中图分类号:  (Colloids)

  • 64.70.pv
64.70.qj (Dynamics and criticality) 61.05.fg (Neutron scattering (including small-angle scattering))