Yielding and flow of foamed metakaolin pastes

Ducloué, Lucie; Pitois, Olivier; Tocquer, Laurent; Goyon, Julie; Ovarlez, Guillaume

doi:10.1016/j.colsurfa.2016.11.015

Cited by 15 publications

(9 citation statements)

References 25 publications

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“…Results (figure 4) have shown that the yield stress of emulsion foams depends on coupled effects of capillary pressure, 8 ⁄ , and emulsion yield stress, . Those parameters can be used to form the Bingham-capillary number [25,26,29], <= = 8 ⁄ . The reduced yield stress…”

Section: Discussionmentioning

confidence: 99%

“…In fact, little is known about rheology of complex liquid foams while such knowledge is crucial for applications. Yield stress properties allow the material to sustain external forces and to keep its initial shape under gravity [25,27,29]. For example, the thickness of a material layer that can be deposited on vertical substrates is directly related to the material yield stress and effective material density.…”

Section: Introductionmentioning

confidence: 99%

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Yielding of complex liquid foams

Gorlier

Khidas

Pitois

2017

Journal of Rheology

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International audienceFoamy complex matter is increasingly encountered in various application fields. Whereas final functional properties of hardened foams have been widely investigated, rheology of complex foamy materials has received less attention. Here, we consider two different types of complex matter to be mixed with aqueous foam and we investigate the resulting yield stress, which is known to control both static and flow properties of foams: (1) A concentrated emulsion possessing intrinsic yield stress properties and (2) granular suspensions which are known to exhibit particle size effects when incorporated into foam. Yield stress of emulsion foams is found to be governed by both the Bingham-capillary number (i.e., the emulsion yield stress scaled by the bubble capillary pressure) and the volume fraction of interstitial emulsion. Foams made with small solid particles reveal granular packings confined between foam bubbles and the resulting yield stress is shown also to be governed by the Bingham-capillary number, here based on Mohr-Coulomb criterion applied to the interstitial granular material. Yield stress of foams made with large particles is well described by the theory developed from micromechanics of particle-loaded yield stress materials, suggesting that for such size ratios, foam can be considered as a continuous matrix. Within the range of intermediate size ratio values, the normalized foam yield stress undergoes an exponential decay that seems to be related to the number of bubbles separating neighboring particles. Finally, reported results are used to estimate the thicknesses of a foamed material, such as isolating foamed mortars, that can be deposited on vertical substrates

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Yielding of complex liquid foams

Gorlier

Khidas

Pitois

2017

Journal of Rheology

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“…In the elaboration of optimized foamed materials, the rheological behavior of those complex foams is also of primary interest. For example, elasticity and yield stress properties allow the material to sustain external forces and to keep its initial shape under gravity [20][21][22]. In contrast, filling of molds requires an appropriate workability of the fresh foamy paste.…”

Section: Introductionmentioning

confidence: 99%

Optimal strengthening of particle-loaded liquid foams

et al. 2017

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Foams made of complex fluids such as particle suspensions have a great potential for the development of advanced aerated materials. In this paper, we study the rheological behavior of liquid foams loaded with granular suspensions. We focus on the effect of small particles, i.e., particle-to-bubble size ratio smaller than 0.1, and we measure the complex modulus as a function of particle size and particle volume fraction. With respect to previous work, the results highlight a new elastic regime characterized by unequaled modulus values as well as independence of size ratio. A careful investigation of the material microstructure reveals that particles organize through the network between the gas bubbles and form a granular skeleton structure with tightly packed particles. The latter is proven to be responsible for the reported new elastic regime. Rheological probing performed by strain sweep reveals a two-step yielding of the material: The first one occurs at small strain and is clearly attributed to yielding of the granular skeleton; the second one corresponds to the yielding of the bubble assembly, as observed for particle-free foams. Moreover, the elastic modulus measured at small strain is quantitatively described by models for solid foams in assuming that the granular skeleton possesses a bulk elastic modulus of order 100 kPa. Additional rheology experiments performed on the bulk granular material indicate that this surprisingly high value can be understood as soon as the magnitude of the confinement pressure exerted by foam bubbles on packed grains is considered.

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“…Previous studies were mainly focused on drainage and stability issues [4][5][6][7][8][9][12][13][14][15][16][17]19,20 because those two processes jeopardize fresh (not solidified) foamed materials. In contrast, only few studies have tackled rheological issues, for all types of foamed suspensions 5,12,13,22,23,[25][26][27][28][29][30] . However, in the elaboration of optimized foamed materials, the rheological behavior of fresh complex foam is of primary interest also.…”

Section: Introductionmentioning

confidence: 99%

“…However, in the elaboration of optimized foamed materials, the rheological behavior of fresh complex foam is of primary interest also. For example, elasticity and yield stress properties allow the material to sustain external forces and to keep its initial shape under gravity 26,27,29 . In contrast, filling of molds requires appropriate workability of the fresh foamy material.…”

Section: Introductionmentioning

confidence: 99%

Elasticity of particle-loaded liquid foams

2017

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Mixing solid particles with liquid foam is a common process used in industry for manufacturing aerated materials. Desire for improvement of involved industrial processes and optimization of resulting foamed materials stimulates fundamental research on those complex mixtures of grains, bubbles and liquid. In this paper, we generate well-controlled particle-loaded liquid foams and we determine their elastic behavior as a function of particle size (6-3000 μm) and particle volume fraction (0-6%). We focus on both the elastic modulus exhibited by the material at small strain and the strain marking the end of the linear elastic regime. Results reveal the existence of a critical particle-to-bubble size ratio triggering a sharp transition between two well-defined regimes. For small size ratios, the behavior is governed by the mechanical properties of the solid grains, which have been proved to pack in the shape of a foam-embedded granular skeleton. In contrast, bubbles elasticity prevails in the second regime, where isolated large particles contribute only weakly to the rheological behavior of the foamed material. The modeling of elasticity for each regime allows for this transition to be normalized and compared with previously reported particle size-induced effects for foam drainage (Haffner et al. J. Colloid Interface Sci., 2015, 458, 200-208) and solid foam mechanics (Khidas et al., Compos. Sci. Technol., 2015, 119, 62-67). This highlights that rheology and the other properties of particle-loaded foams are subjected to the same size-induced morphological transition.

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Yielding and flow of foamed metakaolin pastes

Cited by 15 publications

References 25 publications

Yielding of complex liquid foams

Yielding of complex liquid foams

Optimal strengthening of particle-loaded liquid foams

Elasticity of particle-loaded liquid foams

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