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Title: Dynamical behaviors of structural, constrained and free water in calcium- and magnesium-silicate-hydrate gels

We present the hypothesis that the mechanical properties of cement pastes depend strongly on their porosities. In a saturated paste, the porosity links to the free water volume after hydration. Structural water, constrained water, and free water have different dynamical behavior. Hence, it should be possible to extract information on pore system by exploiting the water dynamics. With our experiments we investigated the slow dynamics of hydration water confined in calcium- and magnesium-silicate-hydrate (C-S-H and M-S-H) gels using high-resolution quasi-elastic neutron scattering (QENS) technique. C-S-H and M-S-H are the chemical binders present in calcium rich and magnesium rich cements. We measured three M-S-H samples: pure M-S-H, M-S-H with aluminum-silicate nanotubes (ASN), and M-S-H with carboxyl group functionalized ASN (ASN-COOH). A C-S-H sample with the same water content (i.e. 0.3) is also studied for comparison. We found that structural water in the gels contributes to the elastic component of the QENS spectrum, while constrained water and free water contribute the quasi-elastic component. The quantitative analysis suggests that the three components vary for different samples and indicate the variance in the system porosity, which controls the mechanical properties of cement pastes.
ORCiD logo [1] ;  [2] ;  [1] ;  [1] ;  [3] ; ORCiD logo [2] ;  [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Nuclear Science and Engineering
  2. Univ. of Florence (Italy). Dept. of Chemistry "Ugo Schiff" and CSGI
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; FG02- 90ER45429; FG02-90ER45429
Accepted Manuscript
Journal Name:
Journal of Colloid and Interface Science
Additional Journal Information:
Journal Volume: 469; Journal Issue: C; Journal ID: ISSN 0021-9797
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Water dynamics; Porous material; Quasi-elastic neutron scattering; Calcium-silicate-hydrate; Magnesium-silicate-hydrate
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1346258