@article {622, title = {The Potential of Mean Force concept for bridging (length and time) scales in the modeling of complex porous materials}, journal = {EPJ Web of Conferences}, volume = {140}, year = {2017}, month = {Jun-30-2017}, pages = {Article Number 01009}, abstract = {

We introduce the concept of Potential of Mean Force, PMF, as a way to implement upscaling modeling from the nano-scale to micron-scale. A PMF is a free energy function representing in an effective way the interactions between objects (cement hydrates, clay platelets, etc.) at thermodynamics conditions. The PMF is therefore the key piece of information allowing to coarse-grained Physical-Chemistry information in a meso-scale model formulation. The use of PMF offers a huge computational advantage as it allows a straight up-scaling to the meso-scale while keeping essential interactions information that are the hallmark of Physical-Chemistry processes. Such a coarse-grained modeling integrates atomistic response into inter-particle potentials that fully propagate molecular scale information all the way to the meso-scale.

}, doi = {10.1051/epjconf/201714001009}, url = {http://www.epj-conferences.org/10.1051/epjconf/201714001009}, author = {Katerina Ioannidou and Benoit Carrier and Matthieu Vandamme and Roland Jean-Marc Pellenq}, editor = {Farhang Radja{\"\i} and Saeid Nezamabadi and Luding, S. and Jean-Yves Delenne} } @book {636, title = {Springer Series in Geomechanics and GeoengineeringAdvances in Laboratory Testing and Modelling of Soils and Shales (ATMSS)Measurement of Mechanical Properties of Thin Clay Films and Comparison with Molecular Simulations}, series = {Springer Series in Geomechanics and Geoengineering}, year = {2017}, pages = {78-84}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {

Here, we focus on the hydromechanical behavior of self-standing clay films with a thickness of a few dozen microns. We measure their elastic and creep properties and how those properties depend on the interlayer cation and on the relative humidity (or water content). Those experimental results are compared with the elastic and creep behavior of nanometric clay particles, which we characterize by molecular simulations. Significant qualitative differences between the behavior of the clay films and that of the clay particles are observed, which suggests that the hydromechanical behavior of the clay films is significantly impacted by their mesostructure (i.e., by how the clay particles or tactoids are arranged in space). Upscaling the hydromechanical behavior of the clay films from that of the clay particles may be challenging.

}, isbn = {978-3-319-52772-7}, issn = {1866-8755}, doi = {10.1007/978-3-319-52773-410.1007/978-3-319-52773-4_8}, url = {http://link.springer.com/10.1007/978-3-319-52773-4}, author = {Benoit Carrier and Matthieu Vandamme and Roland Jean-Marc Pellenq and Henri Van Damme}, editor = {Ferrari, Alessio and Laloui, Lyesse} } @article {217, title = {Effect of Water on Elastic and Creep Properties of Self-Standing Clay Films}, journal = {Langmuir}, volume = {32}, year = {2016}, month = {Feb-09-2016}, pages = {1370 - 1379}, abstract = {

We characterized experimentally the elastic and creep properties of thin self-standing clay films, and how their mechanical properties evolved with relative humidity and water content. The films were made of clay montmorillonite SWy-2, obtained by evaporation of a clay suspension. Three types of films were manufactured, which differed by their interlayer cation: sodium, calcium, or a mixture of sodium with calcium. The orientational order of the films was characterized by X-ray diffractometry. The films were mechanically solicited in tension, the resulting strains being measured by digital image correlation. We measured the Young\&$\#$39;s modulus and the creep over a variety of relative humidities, on a full cycle of adsorption-desorption for what concerns the Young\&$\#$39;s modulus. Increasing relative humidity made the films less stiff and made them creep more. Both the elastic and creep properties depended significantly on the interlayer cation. For the Young\&$\#$39;s modulus, this dependence must originate from a scale greater than the scale of the clay layer. Also, hysteresis disappeared when plotting the Young\&$\#$39;s modulus versus water content instead of relative humidity. Independent of interlayer cation and of relative humidity greater than 60\%, after a transient period, the creep of the films was always a logarithmic function of time. The experimental data gathered on these mesoscale systems can be of value for modelers who aim at predicting the mechanical behavior of clay-based materials (e.g., shales) at the engineering macroscopic scale from the one at the atomistic scale, for them to validate the first steps of their upscaling scheme. They provide also valuable reference data for bioinspired clay-based hybrid materials.

}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.5b03431}, author = {Benoit Carrier and Matthieu Vandamme and Roland Jean-Marc Pellenq and Bornert, Michel and Ferrage, Eric and Hubert, Fabien and Henri Van Damme} } @proceedings {333, title = {Creep of Clay: Numerical Results at the Scale of a Layer and Experimental Results at the Scale of Thin Self-Standing Films}, journal = {10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete StructuresCONCREEP 10}, volume = {CONCREEP 10: MECHANICS AND PHYSICS OF CREEP, SHRINKAGE, AND DURABILITY OF CONCRETE AND CONCRETE STRUCTURES }, year = {2015}, month = {Sep-17-2015}, pages = {531-536}, publisher = {American Society of Civil Engineers}, address = {September 21{\textendash}23, 2015, Vienna, AustriaReston, VA}, abstract = {

This work focuses on the creep of clay-based materials, which exhibit significant analogies with cement-based materials. Here, we studied the creep of clay at two scales and with two techniques: numerically (with molecular simulations) at the scale of a clay layer (nm), and experimentally at the scale of thin self-standing clay films (few dozen m). At the scale of the clay layer, numerical simulations showed that the shear rate was constant over time and an affine function of the shear stress. Creep experiments showed that, after a transient period, the creep function of our thin self-standing clay films was a logarithmic function of time. A comparison of the results obtained at the two scales shows that the origin of the logarithmic feature of clay creep must at least partly originate from a scale greater than that of an individual clay layer. By analogy, such result is likely to hold for cementitious materials, which are also known to creep logarithmically with respect to time in the long term: the origin of this logarithmic feature is likely to stem at least partly from a scale greater than the scale of an individual C-S-H layer.

}, doi = {10.1061/978078447934610.1061/9780784479346.064}, author = {Benoit Carrier and Matthieu Vandamme and Roland Jean-Marc Pellenq and Henri Van Damme}, editor = {Hellmich, Christian and Pichler, Bernhard and Kollegger, Johann} } @article {114, title = {Elastic Properties of Swelling Clay Particles at Finite Temperature upon Hydration}, journal = {Journal of Physical Chemistry C}, volume = {118}, year = {2014}, month = {May-01-2014}, pages = {8933-8943}, type = {Article}, abstract = {
Abstract Image

The knowledge of mechanical properties of swelling clays on the scale of the clay layer is of crucial importance to build predictive hydromechanical macroscopic constitutive laws in a bottom-up approach. In this work, we computed the elastic properties of particles of a swelling clay (i.e., montmorillonite) by molecular dynamics simulations. Because of the softness of the material in the direction orthogonal to the clay layer with increasing water content, the computation of the whole stiffness tensor was not trivial: we needed to implement the elastic bath method,1 which allows us to attenuate thermal strains and compute the stiffness via strain fluctuations in isothermal\–isobaric simulations. We investigated the effect of water content, temperature, and the interlayer cation on the elastic properties of swelling clays. In particular, we showed that the out-of-plane stiffness coefficients computed at 300 K differed significantly from the same coefficients computed at 0 K. The out-of-plane coefficients were very sensitive to both temperature and water content. In contrast, the dependence of the in-plane coefficients to temperature was slight. Moreover, the decrease of the in-plane coefficients with water content could be entirely explained by the change of geometry of the system due to the swelling of the interlayer space. The interlayer cation impacted the elastic properties of montmorillonite only in the driest states.

}, issn = {1932-7447}, doi = {10.1021/jp412160e}, author = {Benoit Carrier and Matthieu Vandamme and Roland Jean-Marc Pellenq and Henri Van Damme} } @article {46, title = {ESEM Study of the Humidity-Induced Swelling of Clay Film}, journal = {Langmuir}, volume = {29}, year = {2013}, month = {Oct-02-2013}, pages = {12823{\textendash}12833}, abstract = {
Abstract Image

We measured the humidity-induced swelling of thin self-standing films of montmorillonite clay by a combination of environmental scanning electron microscopy (ESEM) and digital image correlation (DIC). The films were about 40 \μm thick. They were prepared by depositing and evaporating a suspension of clay and peeling off the highly oriented deposits. The rationale for creating such original samples was to obtain mesoscopic samples that could be used to bridge experimentally the gap between the scale of the clay layer and the engineering scale of a macroscopic clay sample. Several montmorillonite samples were used: the reference clay Swy-2, the same clay homoionized with sodium or calcium ions, and a sodium-exchanged Cloisite. The edges of the clay films were observed by ESEM at various relative humidity values between 14\% and 95\%. The ESEM images were then analyzed by DIC to measure the swelling or the shrinkage of the films. We also measured the adsorption/desorption isotherms by weighing the film samples in a humidity-controlled environment. In order to analyze our results, we compared our swelling/shrinkage and adsorption/desorption data with previously published data on the interlayer spacing obtained by X-ray diffraction and with numerical estimates of the interlayer water obtained by molecular dynamics simulation. The swelling and the hysteresis of this swelling were found to be comparable for the overall macroscopic films and for the interlayer space. The same correspondence between film and interlayer space was observed for the amount of adsorbed water. This suggests that, in the range of relative humidities values explored, the films behave like freely swelling oriented stacks of clay layers, without any significant contribution from the mesoporosity. The relevance of this result for the behavior of clayey sedimentary rocks and the differences with the behavior of nonoriented samples (powders or compacted powders) are briefly discussed.

}, doi = {10.1021/la402781p}, author = {Benoit Carrier and Wang, Linlin and Matthieu Vandamme and Roland Jean-Marc Pellenq and Bornert, Michel and Tanguy, Alexandre and Henri Van Damme} } @article {31, title = {Nanoindentation investigation of creep properties of calcium silicate hydrates}, journal = {Cement and Concrete Research}, volume = {52}, year = {2013}, month = {Oct-2013}, pages = {38{\textendash}52}, abstract = {

The creep properties of calcium silicate hydrates (C-S-H) are assessed by means of nanoindentation creep experiments on a wide range of substoichiometric cement pastes. We observe that, after a few seconds, the measured creep compliance of C-S-H is very well captured by a logarithmic time function. The rate of the logarithmic creep is found to scale in a unique manner with indentation modulus, indentation hardness, and packing density, independent of processing, mix proportions, indenter geometry and load history. The comparison with macroscopic creep experiments on concrete shows that minutes-long nanoindentations enable a quantitative assessment of the long-term creep properties of cementitious materials, orders of magnitude faster than macroscopic testing. Finally, we show that a strong analogy exists between this logarithmic creep behavior of C-S-H and that of soils, which suggests a granular origin of creep of geomaterials.

Typical measurement of variation Δh(t) in penetration depth during the creep ...

Coefficient γ governing the linear part of the fitting function (16) versus (a) ...

}, doi = {10.1016/j.cemconres.2013.05.006}, author = {Matthieu Vandamme and Franz-Josef Ulm} } @article {56, title = {Poromechanics of microporous media}, journal = {Journal of the Mechanics and Physics of Solids}, volume = {60}, year = {2012}, month = {Apr-2012}, pages = {606{\textendash}622}, abstract = {

Microporous media, i.e., porous media made of pores with a nanometer size, are important for a variety of applications, for instance for sequestration of carbon dioxide in coal, or for storage of hydrogen in metal-organic frameworks. In a pore of nanometer size, fluid molecules are not in their bulk state anymore since they interact with the atoms of the solid: they are said to be in an adsorbed state. For such microporous media, conventional poromechanics breaks down.

In this work we derive poroelastic constitutive equations which are valid for a generic porous medium, i.e., even for a porous medium with pores of nanometer size. The complete determination of the poromechanical behavior of a microporous medium requires knowing how the amount of fluid adsorbed depends on both the fluid bulk pressure and the strain of the medium. The derived constitutive equations are validated with the help of molecular simulations on one-dimensional microporous media. Even when a microporous medium behaves linearly in the absence of any fluid (i.e., its bulk modulus does not depend on strain), we show that fluid adsorption can induce non-linear behavior (i.e., its drained bulk modulus can then depend significantly on strain). We also show that adsorption can lead to an apparent Biot coefficient of the microporous medium greater than unity or smaller than zero.

The poromechanical response of a microporous medium to adsorption significantly depends on the pore size distribution. Indeed, the commensurability (i.e., the ratio of the size of the pores to that of the fluid molecules) proves to play a major role. For a one-dimensional model of micropores with a variety of pore sizes, molecular simulations show that the amount of adsorbed fluid depends linearly on the strain of the medium. We derive linearized constitutive equations which are valid when such a linear dependence of the adsorbed amount of fluid on the strain is observed.

As an application, the case of methane and coal is considered. Molecular simulations of an adsorption of methane on a microporous realistic model for coal are performed with a flexible solid skeleton. The applicability of the set of linearized constitutive equations to this case is discussed and the results are shown to be consistent with swelling data measured during a classical adsorption experiment.

Example of molecular configuration. The fluid molecules can enter or leave the ...

Amount of fluid molecules adsorbed per unit length of the undeformed chain, in ...

Apparent tangent drained bulk modulus Kt of the crystalline chain.

}, doi = {10.1016/j.jmps.2012.01.001}, author = {Brochard, Laurent and Matthieu Vandamme and Roland Jean-Marc Pellenq} } @article {260, title = {Quantifying plasticity-independent creep compliance and relaxation of viscoelastoplastic materials under contact loading}, journal = {Journal of Materials Research}, volume = {27}, year = {2012}, month = {Jan-2012}, pages = {302 - 312}, abstract = {

Here we quantify the time-dependent mechanical properties of a linear viscoelastoplastic material under contact loading. For contact load relaxation, we showed that the relaxation modulus can be measured independently of concurrent plasticity exhibited during the loading phase. For indentation creep, we showed that the rate of change of the contact creep compliance can be measured independently of any plastic deformation exhibited during loading through , where a(t) is the contact radius, h(t) is the displacement of the contact probe, and Pmax is the constant applied load during the creep phase. These analytical relations were compared with numerical simulations of conical indentation creep for a viscoelastoplastic material and validated against sharp indentation creep experiments conducted on polystyrene. The derived relations enable extraction of viscoelastic material characteristics, even if sharp probes confer concurrent plasticity, applicable for a general axisymmetric contact probe geometry and a general time-independent plasticity.

}, issn = {0884-2914}, doi = {10.1557/jmr.2011.302}, author = {Matthieu Vandamme and Tweedie, Catherine A. and Constantinides, Georgios and Franz-Josef Ulm and Krystyn J. Van Vliet} } @article {59, title = {Adsorption-induced deformation of microporous materials: coal swelling induced by co2{\textendash}ch4 competitive adsorption}, journal = {Langmuir}, volume = {28}, year = {2011}, month = {Dec-20-2011}, pages = {2659{\textendash}2670}, abstract = {
Abstract Image

Carbon dioxide injection in coal seams is known to improve the methane production of the coal seam, while ensuring a safe and long-term carbon sequestration. This improvement is due to the preferential adsorption of CO2 in coal with respect to CH4: an injection of CO2 thus results in a desorption of CH4. However, this preferential adsorption is also known to cause a differential swelling of coal, which results in a significant decrease in the reservoir permeability during the injection process. Recent studies have shown that adsorption in coal micropores (few angstr\öms in size) is the main cause of the swelling. In this work, we focus on the competitive adsorption behavior of CO2 and CH4 in micropores. We perform molecular simulations of adsorption with a realistic atomistic model for coal. The competitive adsorption is studied at various temperatures and pressures representative of those in geological reservoirs. With the help of a poromechanical model, we then quantify the subsequent differential swelling induced by the computed adsorption behaviors. The differential swelling is almost insensitive to the geological temperatures and pressures considered here and is proportional to the CO2 mole fraction in the coal.

}, doi = {10.1021/la204072d}, author = {Brochard, Laurent and Matthieu Vandamme and Roland Jean-Marc Pellenq and Fen-Chong, Teddy} }