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

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• 作者：Peisi Le^a ; ^{lepeisi@mit.edu" class="auth_mail" title="E-mail the corresponding author} ; Emiliano Fratini^b ; ^{fratini@csgi.unifi.it" class="auth_mail" title="E-mail the corresponding author} ; Kanae Ito^a ; ^{kanae@mit.edu" class="auth_mail" title="E-mail the corresponding author} ; Zhe Wang^a ; ^{zwang10@mit.edu" class="auth_mail" title="E-mail the corresponding author} ; Eugene Mamontov^c ; ^{mamontove@ornl.gov" class="auth_mail" title="E-mail the corresponding author} ; Piero Baglioni^b ; ^{baglioni@csgi.unifi.it" class="auth_mail" title="E-mail the corresponding author} ; Sow-Hsin Chen^a ; ^{sowhsin@mit.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Water dynamics ; Porous material ; Quasi-elastic neutron scattering ; Calcium-silicate-hydrate ; Magnesium-silicate-hydrate
• 刊名：Journal of Colloid and Interface Science
• 出版年：2016
• 出版时间：1 May 2016
• 年：2016
• 卷：469
• 期：Complete
• 页码：157-163
• 全文大小：558 K

文摘

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.

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.

Findings

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.