Back to basics: Nanomodulating calcium silicate hydrate gels to mitigate CO2 footprint of concrete industry

Xinyue Wang, Siqi Ding, Ashraf Ashour, Hailong Ye, Vijay Kumar Thakur, Liqing Zhang, Baoguo Han*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

To realize the sustainable development of concrete, it is vital to mitigate its consumption and environmental footprint (especially CO2 footprint) from prolonging the service life through upgrading mechanical and durable performances of concrete. Incorporating nanofillers can effectively tailor the microstructures and performances of bulk cement paste and cement paste at interfacial transition zone in concrete. The hydrated calcium silicate (C–S–H) gels account for half of the volume of hardened Portland cement pastes, and they are the fundamental source of overall properties of concrete. However, the underlying mechanisms of nanofillers on C–S–H gels remains unclear. Herein, this paper underpinned the role of 5 types of representative nanofillers in tailoring the nanostructure of C–S–H gels in cement composites. The research results demonstrated that through the nano-core effect, nanofillers induce the formation of two new C–S–H gels in outer hydration products, namely nano-core-shell element doped low-density C–S–H (NEDLD C–S–H) and nano-core-shell element doped high-density C–S–H (NEDHD C–S–H). The indentation modulus/hardness of NEDLD and NEDHD C–S–H reaches 25.4/0.80 GPa and 46.7/2.72 GPa, respectively. Such superior performances of NEDLD and NEDHD C–S–H derive from the existence of nano-core-shell elements in C–S–H gels rather than the increase in C–S–H packing density. In a short-range, nanofillers form nano-core-shell elements by adsorbing silica tetrahedrons during the hydration process, improving the mechanical properties of C–S–H basic building blocks. In the long-range, the nano-core-shell elements modify the nano-scale performances of C–S–H gels in outer hydration products due to the increase of C–S–H gels’ integrality.

Original languageEnglish
Article number139921
JournalJournal of Cleaner Production
Volume434
Early online date1 Dec 2023
DOIs
Publication statusPrint publication - 1 Jan 2024

Bibliographical note

Publisher Copyright:
© 2023 Elsevier Ltd

Keywords

  • CO footprint
  • Concrete
  • Hydrated calcium silicate (C–S–H)
  • Nanomodulation

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