title: Effect of chemical environment on the dynamics of water confined in calcium silicate minerals: natural and synthetic tobermorite.
abstract: Confined water in the slit mesopores of the mineral tobermorite provides an excellent model system for analyzing the dynamic properties of water confined in cement-like materials. In this work, we use broadband dielectric spectroscopy (BDS) to analyze the dynamic of water entrapped in this crystalline material. Two samples, one natural and one synthetic, were analyzed, and despite their similar structure, the motion of confined water in their zeolitic cavity displays considerably different behavior. The water dynamics splits into two different behaviors depending on the chemical nature of the otherwise identical structural environment: water molecules located in areas where the primary building units are SiO4 relax slowly compared to water molecules located in cavities built with both AlO4 and SiO4. Compared to water confined in regular porous systems, water restricted in tobermorite is slower, indicating that the mesopore structure induces high disorder in the water structure. A comparison with water confined in the C-S-H gel is also discussed in this work. The strong dynamical changes in water due to the presence of aluminum might have important implications in the chemical transport of ions within hydrated calcium silicates, a process that governs the leaching and chemical degradation of cement.
authors: †Centro de Fisica de Materiales (CSIC, UPV/EHU)-Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain.
authors: Manuel
authors: M
authors: Monasterio
authors: Juan J
authors: JJ
authors: Gaitero
authors: §Molecular Spectroscopy Laboratory, University of Basque Country UPV EHU, Bilbao 48080, Spain.
authors: Hegoi
authors: H
authors: Manzano
authors: Jorge S
authors: JS
authors: Dolado
authors: †Centro de Fisica de Materiales (CSIC, UPV/EHU)-Materials Physics Center (MPC), Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain.|∥Donostia International Physics Center, 20018 San Sebastián, Spain.
authors: Silvina
authors: S
authors: Cerveny
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D002197:Capillary Action; D058266:Dielectric Spectroscopy; D008903:Minerals / Q000737:chemistry*; D016062:Porosity; D017640:Silicates / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D017155:Wettability
chemical_list: D017610:Calcium Compounds; D008903:Minerals; D017640:Silicates; D014867:Water; C512534:tobermorite; D000537:Aluminum Oxide; C031293:calcium silicate