title: Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates.
abstract: Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of (29)Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the hydration process in terms of transient local molecular composition, extent of silicate hydration and polymerization. This provides insights on the relative influence of surface hydroxylation and hydrate precipitation on the hydration rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured.
authors.affiliation: Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich 8093, Switzerland.
authors.forename: Elizaveta
authors.initials: E
authors.lastname: Pustovgar
authors.affiliation: Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
authors.forename: Rahul P
authors.initials: RP
authors.lastname: Sangodkar
authors.affiliation: Soft Matter Science and Engineering Laboratory, UMR CNRS 7615, ESPCI Paris, PSL Research University, 10 rue Vauquelin, Paris 75005, France.
authors.forename: Andrey S
authors.initials: AS
authors.lastname: Andreev
authors.affiliation: Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich 8093, Switzerland.
authors.forename: Marta
authors.initials: M
authors.lastname: Palacios
authors.affiliation: Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
authors.forename: Bradley F
authors.initials: BF
authors.lastname: Chmelka
authors.affiliation: Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich 8093, Switzerland.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Flatt
authors.affiliation: Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich 8093, Switzerland.|Soft Matter Science and Engineering Laboratory, UMR CNRS 7615, ESPCI Paris, PSL Research University, 10 rue Vauquelin, Paris 75005, France.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: d'Espinose de Lacaillerie