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Article

An Atomistic Model Describing the Structure and Morphology of Cu-Doped C-S-H Hardening Accelerator Nanoparticles

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Institute of Geosciences and Earth Resources, National Research Council of Italy, Via G. Gradenigo 6, 35131 Padova, Italy
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Department of Geosciences and CIRCe Centre, University of Padova, Via G. Gradenigo 6, 35131 Padova, Italy
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MAPEI Spa, R&D Laboratory, 20158 Milano, Italy
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Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
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Institute of Condensed Matter Chemistry and Technologies for Energy, National Research Council of Italy, Corso Stati Uniti 4, 35127 Padova, Italy
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Department of Science and High Technology and To.Sca.Lab, University of Insubria, Via Valleggio 11, 22100 Como, Italy
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Institute of Crystallography and To.Sca.Lab, National Research Council of Italy, Via Valleggio 11, 22100 Como, Italy
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Department of Earth Sciences, University of Turin, Via Valperga Caluso 35, 10125 Torino, Italy
*
Author to whom correspondence should be addressed.
Academic Editor: Andrey B. Evlyukhin
Nanomaterials 2022, 12(3), 342; https://doi.org/10.3390/nano12030342
Received: 24 December 2021 / Revised: 13 January 2022 / Accepted: 17 January 2022 / Published: 21 January 2022
(This article belongs to the Special Issue Total Scattering Based Characterization Techniques for Nanostructures)
Calcium silicate hydrate (C-S-H) is the main binding phase in Portland cement. The addition of C-S-H nanoparticles as nucleation seeds has successfully been used to accelerate the hydration process and the precipitation of binding phases either in conventional Portland cement or in alternative binders. Indeed, the modulation of the hydration kinetics during the early-stage dissolution-precipitation reactions, by acting on the nucleation and growth of binding phases, improves the early strength development. The fine-tuning of concrete properties in terms of compressive strength and durability by designed structural modifications can be achieved through the detailed description of the reaction products at the atomic scale. The nano-sized, chemically complex and structurally disordered nature of these phases hamper their thorough structural characterization. To this aim, we implement a novel multi-scale approach by combining forefront small-angle X-ray scattering (SAXS) and synchrotron wide-angle X-ray total scattering (WAXTS) analyses for the characterization of Cu-doped C-S-H nanoparticles dispersed in a colloidal suspension, used as hardening accelerator. SAXS and WAXTS data were analyzed under a unified modeling approach by developing suitable atomistic models for C-S-H nanoparticles to be used to simulate the experimental X-ray scattering pattern through the Debye scattering equation. The optimization of atomistic models against the experimental pattern, together with complementary information on the structural local order from 29Si solid-state nuclear magnetic resonance and X-ray absorption spectroscopy, provided a comprehensive description of the structure, size and morphology of C-S-H nanoparticles from the atomic to the nanometer scale. C-S-H nanoparticles were modeled as an assembly of layers composed of 7-fold coordinated Ca atoms and decorated by silicate dimers and chains. The structural layers are a few tens of nanometers in length and width, with a crystal structure resembling that of a defective tobermorite, but lacking any ordering between stacking layers. View Full-Text
Keywords: calcium silicate hydrate; cement hardening accelerator; Debye scattering equation; small-angle X-ray scattering; wide-angle X-ray total scattering; 29Si MAS-NMR; EXAFS; nanostructure calcium silicate hydrate; cement hardening accelerator; Debye scattering equation; small-angle X-ray scattering; wide-angle X-ray total scattering; 29Si MAS-NMR; EXAFS; nanostructure
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MDPI and ACS Style

Dal Sasso, G.; Dalconi, M.C.; Ferrari, G.; Pedersen, J.S.; Tamburini, S.; Bertolotti, F.; Guagliardi, A.; Bruno, M.; Valentini, L.; Artioli, G. An Atomistic Model Describing the Structure and Morphology of Cu-Doped C-S-H Hardening Accelerator Nanoparticles. Nanomaterials 2022, 12, 342. https://doi.org/10.3390/nano12030342

AMA Style

Dal Sasso G, Dalconi MC, Ferrari G, Pedersen JS, Tamburini S, Bertolotti F, Guagliardi A, Bruno M, Valentini L, Artioli G. An Atomistic Model Describing the Structure and Morphology of Cu-Doped C-S-H Hardening Accelerator Nanoparticles. Nanomaterials. 2022; 12(3):342. https://doi.org/10.3390/nano12030342

Chicago/Turabian Style

Dal Sasso, Gregorio, Maria C. Dalconi, Giorgio Ferrari, Jan S. Pedersen, Sergio Tamburini, Federica Bertolotti, Antonietta Guagliardi, Marco Bruno, Luca Valentini, and Gilberto Artioli. 2022. "An Atomistic Model Describing the Structure and Morphology of Cu-Doped C-S-H Hardening Accelerator Nanoparticles" Nanomaterials 12, no. 3: 342. https://doi.org/10.3390/nano12030342

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