Water dynamics in calcium silicate hydrates probed by inelastic neutron scattering and molecular dynamics simulations

Z Zhakiyeva and V Magnin and A Poulain and S Campillo and MP Asta and R Besselink and S Gaboreau and F Claret and S Grangeon and S Rudic and S Rols and M Jiménez-Ruiz and IC Bourg and AES Van Driessche and GJ Cuello and A Fernández-Martínez, CEMENT AND CONCRETE RESEARCH, 184, 107616 (2024).

DOI: 10.1016/j.cemconres.2024.107616

Calcium-silicate-hydrate (C-S-H) is a disordered, nanocrystalline material, acting as a primary binding phase in Portland cement. C-S-H and C-A-S-H (an Al-bearing substitute present in low-CO2 2 cement) contain thin films of water on solid surfaces and inside nanopores. Water controls multiple chemical and mechanical properties of C-S- H, including drying shrinkage, ion transport, creep, and thermal behavior. Therefore, obtaining a fundamental understanding of its properties is essential. We applied a combination of inelastic incoherent neutron scattering and molecular dynamics simulations to unravel water dynamics in synthetic C-(A)-S-H conditioned at five hydration states (from drier to more hydrated) and with three Ca/Si ratios (0.9, 1, and 1.3). Our results converge towards a picture where the evolution from thin layers of interfacial water to bulk-like capillary water is dampened by the structure of C-(A)-S-H. In particular, the hydrophilic Ca2+ 2 + sites organize the distribution of interfacial C-(A)-S-H water.

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