The mechanisms of plaster drying

Seck, M.; Landeghem, Maxime Van; Faure, Paméla; Rodts, Stéphane; Combes, R.; Cavalie, P; Keita, Emmanuel; Coussot, Philippe

doi:10.1007/s10853-014-8807-x

Cited by 16 publications

(20 citation statements)

References 16 publications

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“…(see Figure 1). As already explained in [13] this result contrasts with the well-known effect of constant drying rate down to a saturation of the order of 10% (at sufficiently low air flow velocity) for a simple porous medium filled with a pure hydrophilic liquid [47][48]. Indeed, during drying simple materials exhibit a first regime, called the CRP (Constant Rate Period), during which the drying rate is approximately constant.…”

Section: Resultsmentioning

confidence: 80%

“…the ratio of the mass of water to the mass of powder, was between 0.5 and 0.8. At the end of the hydration reaction (after about 25 min, as found from NMR measurements [13]) which consumed about 20% of the initial water mass, the solid structure is filled with a calcium -sulphate solution at the gypsum solubility limit ( =2.65 g/l). This porous medium has initially a homogeneous porosity of 58% and a bimodal pore size distribution (from Mercury Intrusion Porosimetry) with peaks at 0.6 and 5 microns or so. )…”

Section: Methodsmentioning

confidence: 95%

“…, as a function of  . Such data are reproducible with an uncertainty of about 20% on the drying rate [13] in particular due to the slight variations of the surface shape of the samples and the data processing to compute…”

Section: Methodsmentioning

confidence: 99%

“…The impurities are mainly clay (colloidal) particles. Our plaster paste samples are prepared according to a well-defined mixing protocol [13,43]. The initial water to powder ratio (w/p), i.e.…”

Section: Methodsmentioning

confidence: 99%

“…Previous studies concerning plaster properties during its preparation focused on the structure evolution in time, in particular with the help of NMR, showing that the pore distribution evolves as a result of hydration [11][12]. A recent work finally showed that the drying rate of plaster pastes is significantly lower than that expected for a pure liquid evaporating from a simple homogeneous porous medium [13]. This effect was shown to be enhanced by the air flow velocity and the initial solid/water ratio.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Subflorescence and plaster drying dynamics

Seck

Keita

Faure

et al. 2016

Chemical Engineering Science

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The dynamics of plaster drying and the impact of subflorescence on the process are described through Magnetic Resonance Imaging and X-Ray Microtomography measurements. It is shown that crystals deposit around the air-liquid interface the closest to the sample free surface, which induces a recession of this interface within the sample at a rate only depending on the current saturation (water to pore volume ratio). Thus the distribution of crystals deposited during evaporation essentially depends on the history of saturation. The drying dynamics then results from vapor diffusion through the less porous layers of crystal accumulation below the sample free surface. This in particular makes it possible to predict the dramatic decrease of the drying rate after successive imbibition-drying cycles.

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Section: Resultsmentioning

confidence: 80%

Section: Methodsmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Subflorescence and plaster drying dynamics

Seck

Keita

Faure

et al. 2016

Chemical Engineering Science

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Progress in rheology and hydrodynamics allowed by NMR or MRI techniques

Coussot

2020

Exp Fluids

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We review the uses of nuclear magnetic resonance techniques for experiments with fluids. More precisely we focus on the progress of knowledge in complex flows, rheology of complex fluids, flow in porous media, colloid transport, fluid transfers in complex porous systems, which have been allowed by NMR techniques. These achievements took advantage of the versatility of NMR, which makes it possible to carry out more original measurements than the basic well-known density imaging (MRI). One may thus rely on non-destructive, non-invasive, local velocimetry, local rheometry, statistical approaches of molecular displacements or velocity, distribution of adsorbed or suspended colloids, evolution of the liquid distribution in different states, fluid transfers during drying or imbibition, etc.

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Some Observations on the Impact of a Low-Solubility Ionic Solution on Drying Characteristics of a Model Porous Medium

2018

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We study the impact on the drying rate, of the presence of suspended elements, such as calcium sulfate ions with a low solubility, in the interstitial fluid of a porous medium. In order to single out this process in the complexity of a porous medium, we study it through drying in a simple capillary exhibiting characteristics such that it reproduces some critical aspects of drying of porous media. Another specificity of our work is that we focus on the evaporation of initially ion saturated solutions. We first show that in such a capillary the drying process varies depending on the wettability characteristics. Typically the drying rate is much smaller with hydrophobic surfaces because of the airliquid interface which tends to withdraw inside the medium, while for hydrophilic surfaces there remains a continuous liquid film up to the entrance. Then it appears that an ionic solution dries slower than a pure liquid, because the crystals formed along the capillary walls tend to induce a dewetting of the capillary entrance, pushing inwards the first liquid-air interface from which most of the evaporation occurs. An experiment with a model colloidal suspension further illustrates this mechanism: the accumulation of solid particles along the wall forms a deposit which pushes inwards the first liquid-air interface from which evaporation takes place. Finally we look at the impact, on the drying characteristics, of the presence of different additives in the ionic solution.

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The mechanisms of plaster drying

Cited by 16 publications

References 16 publications

Subflorescence and plaster drying dynamics

Subflorescence and plaster drying dynamics

Progress in rheology and hydrodynamics allowed by NMR or MRI techniques

Some Observations on the Impact of a Low-Solubility Ionic Solution on Drying Characteristics of a Model Porous Medium

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