Structure of Water Adsorbed on Nanocrystalline Calcium Silicate Hydrate Determined from Neutron Scattering and Molecular Dynamics Simulations
Z Zhakiyeva and GJ Cuello and HE Fischer and DT Bowron and C Dejoie and V Magnin and S Campillo and S Bureau and A Poulain and R Besselink and S Gaboreau and S Grangeon and F Claret and IC Bourg and AES Van Driessche and A Fernandez-Martinez, JOURNAL OF PHYSICAL CHEMISTRY C, 126, 12820-12835 (2022).
Calcium silicate hydrate (C-S-H) is a disordered, nanocrystalline material that acts as a primary binding phase in Portland cement. Thin films of water are present on the surfaces and in nanopores of C-S-H, impacting many of its chemical and mechanical properties, such as ion transport, creep, or thermal behavior. Despite decades of research, a full understanding of the structural details of adsorbed, confined, and bulk water in C-S-H remains elusive. In this work, we applied a multitechnique study involving molecular dynamics (MD) simulations validated by neutron diffraction with isotopic substitution (NDIS) and X-ray scattering methods to investigate the structure of water in C-S-H and C-A-S-H (an Al-bearing, low-CO2 C-S-H substitute). Direct comparison of NDIS data with the MD results reveals that the structure of confined and interfacial water differs significantly from the bulk water and exhibits a larger degree of mesoscale ordering for more hydrated C-S-H structures. This observation suggests an important role of water as a stabilizer of the atomistic-level structure of C-S-H.
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