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

• Published in: Cement and concrete research 2024-10, Vol.184, p.107616, Article 107616
• Main Authors: Zhakiyeva, Zhanar, Magnin, Valérie, Poulain, Agnieszka, Campillo, Sylvain, Asta, María P., Besselink, Rogier, Gaboreau, Stéphane, Claret, Francis, Grangeon, Sylvain, Rudic, Svemir, Rols, Stéphane, Jiménez-Ruiz, Mónica, Bourg, Ian C., Van Driessche, Alexander E.S., Cuello, Gabriel J., Fernández-Martínez, Alejandro
• Format: Article
• Language: English
• Subjects: C-(A)-S-H; Earth Sciences; Inelastic neutron scattering; Interfacial water; Low CO2 cements; Molecular dynamics simulations; Nanoporous vs bulk-like water; Sciences of the Universe; Water dynamics
• ISSN: 0008-8846; 1873-3948
• 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 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+ sites organize the distribution of interfacial C-(A)-S-H water.