title: Cause of the fragile-to-strong transition observed in water confined in C-S-H gel.
abstract: In this study, the rotational dynamics of hydration water confined in calcium-silicate-hydrate (C-S-H) gel with a water content of 22 wt.% was studied by broadband dielectric spectroscopy in broad temperature (110-300 K) and frequency (10(-1)-10(8) Hz) ranges. The C-S-H gel was used as a 3D confining system for investigating the possible existence of a fragile-to-strong transition for water around 220 K. Such transition was observed at 220 K in a previous study [Y. Zhang, M. Lagi, F. Ridi, E. Fratini, P. Baglioni, E. Mamontov and S. H. Chen, J. Phys.: Condens. Matter 20, 502101 (2008)] on a similar system, and it was there associated with a hidden critical point of bulk water. However, based on the experimental results presented here, there is no sign of a fragile-to-strong transition for water confined in C-S-H gel. Instead, the fragile-to-strong transition can be explained by a merging of two different relaxation processes at about 220 K.
authors.affiliation: Centro de Fisica de Materiales (CSIC, UPV∕EHU)-Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Monasterio
authors.forename: Helén
authors.initials: H
authors.lastname: Jansson
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Gaitero
authors.forename: Jorge S
authors.initials: JS
authors.lastname: Dolado
authors.forename: Silvina
authors.initials: S
authors.lastname: Cerveny
mesh_terms: D002118:Calcium / Q000737:chemistry*; D005782:Gels; D044367:Phase Transition; D017640:Silicates / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D005782:Gels; D017640:Silicates; D014867:Water; D002118:Calcium