Drying Shrinkage of Deformable Porous Media: Mechanisms Induced by the Fluid Removal

Hu, Liangbo; Peron, Hervé; Hueckel, Tomasz; Laloui, Lyesse

doi:10.1061/40901(220)17

Cited by 9 publications

(16 citation statements)

References 5 publications

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“…At certain tensile stress conditions, the material may crack. Cracking of the material is observed at the moment coincident with the formation and rupture of liquid bridges, when air entries into the body of the porous material (Hu et al 2007, 2011, 2013a, b, Kowalski and Mielniczuk 2007, Peron et al 2009a, b, 2013. Also other phenomena, such as suction hardening and softening (wetting collapse), are related to the evolution and rupture of liquid bridges (Gili and Alonso 2002).…”

Section: Introductionmentioning

confidence: 94%

Rupture of an evaporating liquid bridge between two grains

et al. 2014

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A b s t r a c tThe study examines rupture of evaporating liquid bridges between two glass spheres. Evolution of the bridge profile has been recorded with the use of high-speed camera. Geometrical characteristics of the bridge were then used to calculate evolution of the variables during the process: Laplace pressure, capillary force, and surface tension force. For the purpose of reference, the bridge evolution is followed also during kinematic extension. During both processes the diameter of the neck decreases, with an acceleration of about 1-2 ms before the rupture. Two distinct rupture modes are observed, depending on the bridge aspect ratio. After the rupture, the mass of liquid splits, forming two separate oscillating drops attached to the spheres, and a suspended satellite droplet. Just before the rupture, an increasing repulsive Laplace pressure, and decreasing negative surface tension force develop. Capillary force follows the trend of the surface tension force, with an accelerating decline. Duration of the whole process and liquid mass stabilization is from 10 to 60 ms.

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Section: Introductionmentioning

confidence: 94%

Rupture of an evaporating liquid bridge between two grains

et al. 2014

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“…The capillary shrinkage of porous material has been investigated in material sciences, especially in the area of concrete and glass materials (Dale et al 1998;Hu et al 2007). Surprisingly, capillary shrinkage of the cellulosic materials has not been researched as widely, considering how much the pore structure and pore formation in the cell wall have been studied within pulp and paper industry.…”

Section: Kraft Fiber Cell Wall Pore Size and Pulp Sheet Densitymentioning

confidence: 99%

Effect of Fiber Wall Pore Structure on Pulp Sheet Density of Softwood Kraft Pulp Fibers

Joutsimo¹,

Asikainen²

2013

BioResources

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In this study fiber cell wall porosity was altered by fiber line simulation in a laboratory. The changes in the fiber cell porosity were analyzed with a water retention value (WRV) test. Pore size distributions were measured by differential scanning calorimetry (DCS), and atomic force microscopy (AFM) was used to determine the cell wall pore area from cross sections of the S2 layer of the cell wall. WRV was shown to correlate with the amount of water in the pores with a diameter of at least 200 nm. Changes in the non-freezing and total bound water did not affect the WRV. The calculated shrinkage forces generated by the capillary forces in different pore cell wall structures correlated with the sheet densities generated by fiber networks. It was observed that the swelling of the cell wall, defined as an increase in the diameter of the cell wall, was most likely not occurring or was very difficult to detect.

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“…The capillary forces between partially wet grains are thought to impart an apparent macroscopic or "sand-castle" strength to the moist granular materials, even in the absence of the intrinsic cohesion or confining stress (see e.g. [1][2][3][4][5][6][7]). Two-grain systems are important not only because they are the most elementary but also because more complex multi-grain liquid bridges will eventually break down to a number of two-grain systems (see e.g.…”

Section: Introductionmentioning

confidence: 99%

Evaporation-induced evolution of the capillary force between two grains

2014

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The evolution of capillary forces during evaporation and the corresponding changes in the geometrical characteristics of liquid (water) bridges between two glass spheres with constant separation are examined experimentally. For comparison, the liquid bridges were also tested for mechanical extension (at constant volume). The obtained results reveal substantial differences between the evolution of capillary force due to evaporation and the evolution due to extension of the liquid bridges. During both evaporation and extension, the change of interparticle capillary forces consists in a force decrease to zero either gradually or via rupture of the bridge. At small separations between the grains (short & wide bridges) during evaporation and at large volumes during extension, there is a slight initial increase of force. During evaporation, the capillary force decreases slowly at the beginning of the process and quickly at the end of the process; during extension, the capillary force decreases quickly at the beginning and slowly at the end of the process. Rupture during evaporation of the bridges occurs most abruptly for bridges with wider separations (tall and thin), sometimes occurring after only 25 % of the water volume was evaporated. The evolution (pinning/depinning) of two geometrical characteristics of the bridge, the diameter of the threephase contact line and the "apparent" contact angle at the solid/liquid/gas interface, seem to control the capillary force evolution. The findings are of relevance to the mechanics of unsaturated granular media in the final phase of drying.

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Drying Shrinkage of Deformable Porous Media: Mechanisms Induced by the Fluid Removal

Cited by 9 publications

References 5 publications

Rupture of an evaporating liquid bridge between two grains

Rupture of an evaporating liquid bridge between two grains

Effect of Fiber Wall Pore Structure on Pulp Sheet Density of Softwood Kraft Pulp Fibers

Evaporation-induced evolution of the capillary force between two grains

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