Microscopic physical basis of the poromechanical behavior of cement-based materials

Title: Microscopic physical basis of the poromechanical behavior of cement-based materials
Author(s): A. Gmira, M. Zabat, R.J.-M. Pellenq, H. Van Damme
Paper category : journal
Serial title: Materials and Structures
Abreviated Serial title: Mater. Struct.
ISSN: 1359-5997
Publisher: RILEM Publications SARL
Volume: 37
Issue: 265
Issue date: 2004-01-01
Publication year: 2004
Pages: 3 - 14
Total Pages: 12
Nb references: 75
Language: English

Abstract: Contrary to other porous materials such as sandstones, bricks or porous glass, the inter-atomic bonding continuity of cement-based materials is far from obvious.
When scrutinized at very microscopic level, continuity of the ioniccovalent bonding in the solid phase is almost everywhere interrupted by water molecules or liquid water films of variable thickness.
Yet, concrete and cement pastes are able to withstand stresses of the same magnitude as rocks.
The purpose of this paper to explore the possible reasons for such a high cohesion in terms of inter-particle forces using general arguments and molecular simulation computations including ab initio quantum chemical methods applied to C-S-H.
As it will be discussed, molecular simulation studies provide strong arguments for predicting that shortand mediumrange attractive electrostatic forces are the essential components of the cohesion of C-S-H with, at short distance (sub-nm), a significant iono-covalent contribution involving strongly localized calcium ions and water molecules and, at larger distance (a few nm), ionic correlation forces involving hydrated and mobile calcium ions in liquid water films.
Only a marginal contribution is expected from van der Waals attraction whereas capillary forces might contribute at a level comparable to that of correlation forces in unsaturated conditions.
The parallel with clay-based earthen construction materials is part of the clue of this rationale.

Online publication: 2003-11-27
Classification: Scientific Reports
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/14101