Molecular Engineering of the Cohesionin Neat and Hybrid Cement Hydrates

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Title: Molecular Engineering of the Cohesionin Neat and Hybrid Cement Hydrates

Author(s): A. Gmira, J. Minet, A. Franceschini, N. Lequeux, R.J.-M. Pellenq, and H. Van Damme

Publication: Special Publication

Volume: 254

Issue:

Appears on pages(s): 29-40

Keywords: C-S-H; cohesion forces; hybrid hydrates; molecular simulation

Date: 10/1/2008

Abstract:
On the basis of recent molecular simulation or experimental studies, we discuss two possible strategies for improving the mechanical properties of cementitious materials by modifying the bonding scheme in the hydrates at molecular level. We focus on the calcium silicate hydrates (C-S-H). A first strategy would be based on the strengthening of the cohesion forces acting between the individual C-S-H lamellae or between their crystallites. Monte Carlo simulations in the primitive model framework and ab initio atomistic calculations suggest that the cohesion of C-S-H is mainly due to a combination of sub-nano range ionic-covalent forces and meso-range ionic correlation forces. Both types of forces may be modified, at least in theory, by changing the nature of the interstitial ions, their hydration state, or the charge density on the C-S-H lamellae.