@article {575, title = {Le Ch{\^a}telier{\textquoteright}s conjecture: Measurement of colloidal eigenstresses in chemically reactive materials}, journal = {Journal of the Mechanics and Physics of Solids}, volume = {112}, year = {2018}, month = {Mar-2018}, pages = {334 - 344}, abstract = {

Volume changes in chemically reactive materials, such as hydrating cement, play a critical role in many engineering applications that require precise estimates of stress and pressure developments. But a means to determine bulk volume changes in the absence of other deformation mechanisms related to thermal, pressure and load variations, is still missing. Herein, we present such a measuring devise, and a hybrid experimental-theoretical technique that permits the determination of colloidal eigenstresses. Applied to cementitious materials, it is found that bulk volume changes in saturated cement pastes at constant pressure and temperature conditions result from a competition of repulsive and attractive phenomena that originate from the relative distance of the solid particles- much as Henry Louis Le Chatelier, the father of modern cement science, had conjectured in the late 19th century. Precipitation of hydration products in confined spaces entails a repulsion, whereas the concurrent reduction in interparticle distance entails activation of attractive forces in charged colloidal particles. This cross-over from repulsion to attraction can be viewed as a phase transition between a liquid state (below the solid percolation) and the limit packing of hard spheres, separated by an energy barrier that defines the temperature-dependent eigenstress magnitude. (C) 2017 Elsevier Ltd. All rights reserved.

Fig. 1. Pressure vessel measurement device for volume changes under constant pressure{\textellipsis}

Fig. 2. Bulk Volume Change measurement results under drained and fluid saturated{\textellipsis}

Fig. 3. Eigenstress Scaling: (a) Normalized eigenstress (|σ*|/max|σ*|) vs

Fig. 4. Eigenstress interpretation: (a) volume fractions vs

}, keywords = {Poromechanics; Colloidal stresses; Cement-based materials; Expansion; Shrinkage}, issn = {00225096}, doi = {10.1016/j.jmps.2017.12.012}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0022509617309985}, author = {Muhannad Abuhaikal and Katerina Ioannidou and Petersen, Thomas and Roland Jean-Marc Pellenq and Franz-Josef Ulm} } @article {266, title = {Lattice Boltzmann modelling of liquid distribution in unsaturated granular media}, journal = {Computers and Geotechnics}, volume = {80}, year = {2016}, month = {Dec-2016}, pages = {353 - 359}, abstract = {

We use capillary condensation simulated by a multiphase Lattice Boltzmann model as a means to generate homogeneous distributions of liquid clusters in 2D granular media. Liquid droplets condense from the vapour phase between and on the grains, and they transform into capillary bonds and liquid clusters as thermodynamic equilibrium is approached. As the amount of condensed liquid is increased, liquid clusters of increasing connectivity are formed and the distribution of liquid undergoes topological transitions until the whole pore space is filled by the liquid. We investigate the cluster statistics and local grain environments. From extensive simulations, we also obtain the mean Laplace pressure as a function of the amount of liquid, which is found to be quite similar to the well-known experimental retention curve in soil mechanics. The tensile stress carried by the grains increases as a function of the amount of condensed liquid up to a peak in the funicular state beyond which the stress falls off as a result of pressure drop inside the merging clusters.

}, issn = {0266352X}, doi = {10.1016/j.compgeo.2016.02.017}, author = {Vincent Richefeu and Farhang Radja{\"\i} and Jean-Yves Delenne} } @article {646, title = {Les mat{\'e}riaux poreux : un domaine scientifique et technologique pluridisciplinaire au futur radieux}, journal = {Mat{\'e}riaux \& Techniques}, volume = {103}, year = {2015}, month = {2015}, pages = {701}, abstract = {

Porous materials cover a broad multidisciplinary scientific and technological domain. They are used in numerous existing and emerging devices and processes related to key societal issues both in environmental protection and for the benefit of the economy. Our choice was to illustrate advances in porous materials through three specific examples: porous materials engineering in the case of organic mesoporous materials prepared from block polymers, modeling and numerical simulation of adsorption of molecular species at the nanoscale and, finally technological applications as thermal insulators.

}, issn = {0032-6895}, doi = {10.1051/mattech/2015050}, url = {http://www.mattech-journal.org/10.1051/mattech/2015050}, author = {Ayral, Andre and Calas-Etienne, Sylvie and Benoit A. Coasne and Deratani, Andr{\'e} and Grande, Daniel and Quemener, Damien and Rossignol, Sylvie} } @article {156, title = {Liquid clustering and capillary pressure in granular media}, journal = {Journal of Fluid Mechanics}, volume = {762}, year = {2015}, month = {Jan-2015}, pages = {Article Number: R5}, abstract = {

By means of extensive lattice Boltzmann simulations, we investigate the process of growth and coalescence of liquid clusters in a granular material as the amount of liquid increases. A homogeneous grain\–liquid mixture is obtained by means of capillary condensation, thus providing meaningful statistics on the liquid distribution inside the granular material. The tensile stress carried by the grains as a function of the amount of condensed liquid reveals four distinct states, with a peak stress occurring at the transition from a primary coalescence process, where the cohesive strength is carried mostly by the grains, to a secondary process governed by the increase of the liquid cluster volumes. We show that the evolution of capillary states is correctly captured by a simple model accounting for the competing effects of the Laplace pressure and grain\–liquid interface.

}, issn = {0022-1120}, doi = {10.1017/jfm.2014.676}, author = {Jean-Yves Delenne and Vincent Richefeu and Farhang Radja{\"\i}} } @proceedings {344, title = {Lattice Boltzmann modeling of liquid clusters in granular media}, journal = {3rd International Symposium on Geomechanics from Micro to Macro}, volume = {Geomechanics from Micro to Macro}, year = {2014}, month = {Dec-03-2014}, pages = {461 - 466}, publisher = {CRC Press}, address = {SEP 01-03-2014 Univ Cambridge, Cambridge, ENGLAND}, abstract = {

We use capillary condensation simulated by a multiphase Lattice Boltzmann model as a means to generate homogeneous distributions of liquid clusters in 2D granular media. Liquid droplets condense from the vapor phase between and on the grains, and they transform into capillary bonds and liquid clusters as thermodynamic equilibrium is approached. As the amount of condensed liquid is increased, liquid clusters of increasing connectivity are formed and the distribution of liquid undergoes topological transitions until the whole pore space is filled by the liquid. We investigate the cluster statistics and local grain environments. From extensive simulations, we also obtain the mean Laplace pressure as a function of the amount of liquid, which is found to be quite similar to the well-known experimental retention curve in soil mechanics.

}, isbn = {978-1-138-02707-7}, doi = {10.1201/b1739510.1201/b17395-83}, author = {Jean-Yves Delenne and Vincent Richefeu and Farhang Radja{\"\i}}, editor = {Kenichi Soga and Krishna Kumar and Giovanna Biscontin and Kuo, Matthew} } @article {25, title = {Large pressure enhancements in confined phases: effect of surface chemistry and roughness}, journal = {J. Chem. Phys.}, volume = {139}, year = {2013}, month = {Oct-10-2013}, chapter = {144701}, abstract = {

Experiments and simulations both suggest that the pressure experienced by an adsorbed phase confined within a carbon nanoporous material can be several orders of magnitude larger than the bulk phase pressure in equilibrium with the system. To investigate this pressure enhancement, we report a molecular-simulation study of the pressure tensor of argon confined in slit-shaped nanopores with walls of various models, including carbon and silica materials. We show that the pressure is strongly enhanced by confinement, arising from the effect of strongly attractive wall forces; confinement within purely repulsive walls does not lead to such enhanced pressures. Simulations with both the Lennard-Jones and Barker-Fisher-Watts intermolecular potentials for argon-argon interactions give rise to similar results. We also show that an increase in the wall roughness significantly decreases the in-pore pressure due to its influence on the structure of the adsorbate. Finally, we demonstrate that the pressures calculated from the mechanical (direct pressure tensor calculations) and the thermodynamic (volume perturbation method) routes yield almost identical results, suggesting that both methods can be used to calculate the local pressure tensor components in the case of these planar geometries.

Image of FIG. 1.
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}, doi = {10.1063/1.4824125}, author = {Yun Long and Jeremy C. Palmer and Benoit A. Coasne and Malgorzata Sliwinska-Bartkowiak and George Jackson and Erich A. Mueller and Keith E. Gubbins} }