title: Mesoscale texture of cement hydrates.
abstract: 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 we unveil the C-S-H mesoscale texture, a crucial step to connect the fundamental scales to the macroscale of engineering properties. We 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. We 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. Our 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.
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; MultiScale Material Science for Energy and Environment, Massachusetts Institute of Technology-CNRS Joint Laboratory at Massachusetts Institute of Technology, Cambridge, MA 02139;
authors: Katerina
authors: K
authors: Ioannidou
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
authors: Konrad J
authors: KJ
authors: Krakowiak
authors: Department of Civil and Environmental Engineering, University of California, Los Angeles, CA 90095;
authors: Mathieu
authors: M
authors: Bauchy
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
authors: Christian G
authors: CG
authors: Hoover
authors: School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom;
authors: Enrico
authors: E
authors: Masoero
authors: Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
authors: Sidney
authors: S
authors: Yip
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
authors: Franz-Josef
authors: FJ
authors: Ulm
authors: Physicochimie des Electrolytes et Nanosystèmes interfaciaux Laboratory, CNRS and University Pierre et Marie Curie, 75252 Paris cedex 5, France;
authors: Pierre
authors: P
authors: Levitz
authors: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; MultiScale Material Science for Energy and Environment, Massachusetts Institute of Technology-CNRS Joint Laboratory at Massachusetts Institute of Technology, Cambridge, MA 02139; Centre Interdisciplinaire de Nanoscience de Marseille, CNRS and Aix-Marseille University, 13288 Marseille cedex 09, France; emanuela.del.gado@georgetown.edu pellenq@mit.edu.
authors: Roland J-M
authors: RJ
authors: Pellenq
authors: Department of Physics and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057 emanuela.del.gado@georgetown.edu pellenq@mit.edu.
authors: Emanuela
authors: E
authors: Del Gado
keywords: cement; mechanics; mesoscale; microstructure; simulations