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Engineering the nano- and the meso-scale bonding scheme in neat and hybrid cement hydrates

Title: Engineering the nano- and the meso-scale bonding scheme in neat and hybrid cement hydrates
Author(s): Ahmed Gmira, Jérôme Minet, Nicolas Lequeux, Roland J.-M. Pellenq, Henri Van Damme
Paper category : conference
Book title: NICOM 2: 2nd International Symposium on Nanotechnology in Construction
Editor(s): Y. de Miguel, A. Porro and P.J.M. Bartos
Print-ISBN: 2-912143-87-X
e-ISBN: 2912143888
Publisher: RILEM Publications SARL
Publication year: 2006
Pages: 73 - 84
Total Pages: 12
Nb references: 19
Language: English

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.
A second strategy, akin to a bio-mimetic or tissue engineering approach, would be to hybridize the hydrates by grafting organic moieties on the mineral lamellae. We show that this is easily achieved by controlled hydrolysis of mixtures of organo-silane precursors. The outcome may be a material with an improved fracture energy.

Online publication: 2005-11-17
Publication type : full_text
Public price (Euros): 0.00

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