Direct synthesis of a solid calcium-silicate-hydrate (C-S-H)

Maddalena, Riccardo and Li, Kefei and Chater, Philip A. and Michalik, Stefan and Hamilton, Andrea (2019) Direct synthesis of a solid calcium-silicate-hydrate (C-S-H). Construction and Building Materials, 223. pp. 554-565. ISSN 0950-0618

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    Abstract

    We present new results on solid (monolithic) synthetic C-S-H made at room temperature from easily obtainable calcium sources (calcium oxide, calcium hydroxide) and nanosilica (w/s = 2) with a 2 minute mixing time. Using synchrotron X-ray diffraction combined with TGA/DSC, 29Si NMR and synchrotron pair distribution function (PDF) data we show that the solid C-S-H is crystallographically similar to the more conventionally made synthetic C-S-H slurry. We show that C-S-H is present after 1 day curing (C/S = 0.81) and no X-ray visible portlandite is present from day 3. PDF data shows that the ordered domain size is 2.5 – 4.5 nm, depending on the fit chosen.