Role of Air Pressure in Drying of Weakly Permeable Materials

Mainguy, M.; Coussy, Olivier; Baroghel-Bouny, Véronique

doi:10.1061/(asce)0733-9399(2001)127:6(582)

Cited by 172 publications

(152 citation statements)

References 34 publications

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“…This is shown by additional convective terms in their respective transport equations. Whereas air pressure can have a significant influence on the drying processes of concrete [Mainguy et al, 2001], the characterization of moisture transport properties of a material require the hypothesis of a constant atmospheric pressure, which is often the case in the modelling of coupled heat and mass transfer [Janssen et al, 2007] or in the modelling of material properties [Scheffler and Plagge, 2010].…”

Section: Isothermal Moisture Transport Equationmentioning

confidence: 99%

“…Water vapour transfer is prevailing over liquid transfer in the lower humidity range, in the absence of a continuous liquid phase in the porous network. Liquid transfer is prevailing in the opposite case, for instance when a building component is in contact with wind-driven rain, or for the study of the drying processes of concrete [Mainguy et al, 2001, Baroghel-Bouny et al, 1999. To model both phases as driven by the same potential (usually p c ) for numerical applications, the Kelvin formula can be used to relate both pressures, although the formulation of their spatial and temporal derivatives leads to additional coupling terms in the equation [Janssen et al, 2007].…”

Section: Isothermal Moisture Transport Equationmentioning

confidence: 99%

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Influence of Diffuse Damage on the Water Vapour Permeability of Fibre-Reinforced Mortar

et al. 2012

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The study of moisture transfer inside building materials is an important issue in building physics. The hygric characterization of such materials has become a common practice for the estimation of the hygrothermal performance of buildings. However, their aging caused by mechanical loading and environmental factors inevitably affects their permeability to moisture ingress, and the knowledge of how this permeability is affected by damage and cracks is still incomplete.The effects of diffuse damage caused by mechanical loading on the water vapour permeability of fibre-reinforced mortar were studied. A full experimental setup is presented including observation of the porous structure, mechanical, and hygric characterization. Uniaxial tensile loading was applied on prismatic samples while their damage level was measured. Then, the moisture content of damaged and undamaged samples was monitored during variations of ambient relative humidity. Two numerical methods are presented and used for the comparison of the water vapour permeability of multiple samples presenting various levels of damage. By this methodology, diffuse damage caused by mechanical loading is shown to have an impact on the water vapour transfer inside the material.

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Section: Isothermal Moisture Transport Equationmentioning

confidence: 99%

Section: Isothermal Moisture Transport Equationmentioning

confidence: 99%

Influence of Diffuse Damage on the Water Vapour Permeability of Fibre-Reinforced Mortar

et al. 2012

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“…Drying can be analyzed through the resolution of liquid water, vapor and dry air mass balance equations. The use of several hypotheses [6,7] allows for considering only the mass balance equation of liquid water:…”

Section: Dryingmentioning

confidence: 99%

“…Mainguy et al [6] and Thiery et al [7] showed that this equation is sufficient for an accurate prediction of the drying of ordinary and high-performance concretes at 20°C with a relative humidity greater than 50%. The capillary pressure and the relative permeability are related to the degree of saturation through van Genuchten's relation [8]:…”

Section: Dryingmentioning

confidence: 99%

Modelling desiccation shrinkage of large structures

Benboudjema

Torrenti²

2013

EPJ Web of Conferences

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Abstract. Drying of cement-based materials induces drying shrinkage, which may cause prestress loss or/and cracking if strains are (self or externally) restrained. Drying shrinkage is difficult to predict, since it depends on the material mix, mechanical and hygral boundary conditions, geometry ... This paper focuses on the study of size effect on final drying shrinkage, which is not well documented in the literature. In the Eurocode 2 (European code model), a reduction factor is applied for large structure, which is in agreement with experimental data of one campaign (found in the literature). Using numerical simulations, it is shown that a large panel of models, including phenomenological models as physical ones (which takes into account of (aging) creep under capillary pressure (assumed to be the physical mechanism for drying shrinkage)), do not predict size effect on final value of drying shrinkage.

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“…As water is present in the porous matrix under the form of gas and liquid, several simulation approaches have explicitly considered both states of water in their modelling assumptions and governing equations (Gawin et al 1996;Whitaker 1977). In spite of such complexity, it has already been shown that the simulation of concrete drying can be simplified and reduced to a single diffusion equation, based on the assumption that the drying of weakly permeable materials is mainly achieved by the transport of moisture in its liquid form (Mainguy et al 2001). In another study BaroghelBouny et al (1999) define internal relative humidity of concrete as the relative humidity (h) of the gaseous phase in equilibrium with the interstitial liquid phase in the pore network of the material.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Humidity Fields in Concrete: Experimental Validation and Parameter Estimation

Oliveira

Azenha

2015

ACT

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The moisture content in concrete structures has an important influence in their behavior and performance. Several validated numerical approaches adopt the governing equation for relative humidity fields proposed in Model Code 1990/2010. Nevertheless there is no integrative study which addresses the choice of parameters for the simulation of the humidity diffusion phenomenon, particularly in concern to the range of parameters forwarded by Model Code 1990/2010. A software based on a Finite Difference Method Algorithm (1D and axisymmetric cases) is used to perform sensitivity analyses on the main parameters in a normal strength concrete. Then, based on the conclusions of the sensitivity analyses, experimental results from nine different concrete compositions are analyzed. The software is used to identify the main material parameters that better fit the experimental data. In general, the model was able to satisfactory fit the experimental results and new correlations were proposed, particularly focusing on the boundary transfer coefficient.

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Role of Air Pressure in Drying of Weakly Permeable Materials

Cited by 172 publications

References 34 publications

Influence of Diffuse Damage on the Water Vapour Permeability of Fibre-Reinforced Mortar

Influence of Diffuse Damage on the Water Vapour Permeability of Fibre-Reinforced Mortar

Modelling desiccation shrinkage of large structures

Simulation of Humidity Fields in Concrete: Experimental Validation and Parameter Estimation

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