Mesoscale texture of cement hydrates

Strength and other mechanical properties of cement and concrete rely upon the formation of calcium–silicate–hydrates (C–S–H) during cement hydration. Controlling structure and properties of the C–S–H phase is a challenge, due to the complexity of this hydration product and of the mechanisms that drive its precipitation from the ionic solution upon dissolution of cement grains in water. Departing from traditional models mostly focused on length scales above the micrometer, recent research addressed the molecular structure of C–S–H. However, small-angle neutron scattering, electron-microscopy imaging, and nanoindentation experiments suggest that its mesoscale organization, extending over hundreds of nanometers, may be more important. Here the authors unveil the C–S–H mesoscale texture, a crucial step to connect the fundamental scales to the macroscale of engineering properties. The authors use simulations that combine information of the nanoscale building units of C–S–H and their effective interactions, obtained from atomistic simulations and experiments, into a statistical physics framework for aggregating nanoparticles. The authors compute small-angle scattering intensities, pore size distributions, specific surface area, local densities, indentation modulus, and hardness of the material, providing quantitative understanding of different experimental investigations. The authors' results provide insight into how the heterogeneities developed during the early stages of hydration persist in the structure of C–S–H and impact the mechanical performance of the hardened cement paste. Unraveling such links in cement hydrates can be groundbreaking and controlling them can be the key to smarter mix designs of cementitious materials.

• Record URL:
  • https://doi.org/10.1073/pnas.1520487113
• Record URL:
  • http://www.pnas.org/content/113/8/2029.abstract
• Authors:
  • Ioannidou, Katerina
  • Krakowiak, Konrad J
  • Bauchy, Mathieu
  • Hoover, Christian G
  • Masoero, Enrico
  • Yip, Sidney
  • Ulm, Franz-Josef
  • Levitz, Pierre
  • Pellenq, Roland J-M
  • Del Gado, Emanuela
• Publication Date: 2016-2-23

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References;
• Pagination: pp 2029-2034
• Serial:
  • Proceedings of the National Academy of Sciences
  • Volume: 113
  • Issue Number: 8
  • Publisher: National Academy of Sciences
  • EISSN: 1091-6490
  • Serial URL: http://www.pnas.org/

Subject/Index Terms

• TRT Terms: Hydrates; Mechanical properties; Microstructure; Simulation; Texture
• Uncontrolled Terms: Cement hydrates; Mesoscale
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 01605274
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 27 2016 9:49AM