Modelling hydraulic conductivity for porous building materials based on a prediction of capillary conductivity at capillary saturation

Knarud, Jon Ivar; Kvande, Tore; Geving, Stig

doi:10.1016/j.ijheatmasstransfer.2021.122457

Cited by 12 publications

(8 citation statements)

References 33 publications

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“…In this matter also further study is needed. Film flow has received little mention in the field of construction materials (but see [100]). In soils, film flow of water is considered to make an important, sometimes dominant, contribution to mass transfer in the range of hydraulic potential Ψ = 100-1.5 × 10 4 m [65-67, 101], corresponding to RH 99-30 percent.…”

Section: Porosity and Tortuositymentioning

confidence: 99%

“…suggest that the interpretation of how WVP data vary with RH and and with material composition could usefully draw on information from the sorption isotherm, since this provides information on film thickness and surface area as a function of RH (or 𝐻). Parts of that programme are implemented in [100] to obtain the film conductivity of several brick and cement-based materials, using however the van Genuchten water retention function 𝜃(𝑝 𝑐 ) rather than the sorption isotherm 𝜃(𝐻).…”

Section: The Moisture State and Film Flowmentioning

confidence: 99%

“…Water-vapour permeability material in different moisture states (or RH). Much of this was set out in[40], and partially developed in[63,100,102].…”

mentioning

confidence: 99%

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Water-vapour permeability of inorganic construction materials

Hamilton

2023

Preprint

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Water-vapour permeability (WVP) data on brick, stone, plaster and cement-based materials from some some seventy publications are reviewed and assessed. Almost all sources use standard cup-test methods or close variants. Comparisons of WVP values from different sources on similar materials confirm that reproducibility between different laboratories is poor. Some deficiencies of cup-test methods are discussed, including uncertainties arising from the use of saturated-salt humidistats and desiccants. There is some evidence that the water-vapour resistance factor decreases with increasing mean relative humidity across the test specimen; and weak evidence that the resistance factor increases with volume-fraction porosity. The contribution of liquid film flow to the measured permeability is discussed. It is concluded that (1) available data are inadequate to establish the fundamental physics of WVP; (2) vapouronly permeability data for engineering purposes should be obtained in dry-cup tests at low humidity; and (3) research studies should aim to integrate the WVP into the framework of unsaturated flow theory.

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Section: Porosity and Tortuositymentioning

confidence: 99%

Section: The Moisture State and Film Flowmentioning

confidence: 99%

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Water-vapour permeability of inorganic construction materials

Hamilton

2023

Preprint

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“…Modeling moisture sources involves questions of rain distribution on façade, rain impact and runoff, rain absorption, and moisture infiltration [12][13][14]. Modeling material properties engages uncertainty regarding anisotropic behavior [15], moisture retention and hysteresis [16], moisture-dependent liquid conductivity [17][18][19], and vapor diffusivity, including uncertainty from lack of property measurements. Modeling masonry involves addressing complexity of material connectivity or interface resistance [20,21], material inhomogeneity, and changing properties along interface planes between brick and mortar [22,23], including moisture penetration and infiltration pathways [24], all dependent on mortar curing and curing moisture content, brick-and-mortar properties, and craftmanship during brick laying [25].…”

Section: Hygrothermal Modelingmentioning

confidence: 99%

“…Table 1 provides an overview of necessary material properties and how they have been determined for the hygrothermal simulation. Key properties, such as the moisture retention and hydraulic conductivity ( [35]), have not been measured but were taken from perceived similar materials and modelled, respectively, where, in addition, modeling of the hydraulic conductivity requires the moisture retention as input [17]. Significant uncertainties are, therefore, introduced.…”

Section: Key Uncertainty Regarding Materials Propertiesmentioning

confidence: 99%

Hygrothermal Simulation of Interior Insulated Brick Wall—Perspectives on Uncertainty and Sensitivity

2023

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Energy retrofit of existing masonry buildings has become attractive to meet demands for reduction in energy consumption. Retrofit may, however, introduce moisture risk that needs to be assessed. Hygrothermal simulation analysis is often conducted in this respect. Nevertheless, hygrothermal simulation of interior insulated bare brick masonry exposed to driving rain can be challenging due to the many aspects involved that determine heat- and moisture-transport behavior, and which should be addressed by an applied model. The present study highlights uncertainty encountered when establishing a hygrothermal simulation model. Furthermore, different modeling choices or simplifications are studied to determine impact on results. As a check of realism, results of 2D simulations are compared to results of a previous laboratory experiment of masonry wall segments subjected to severe rain wetting and subsequent drying. Rain absorption is modeled conservatively, attempting simulation results to envelope experiment results. Conservative results were not achieved for a relative humidity sensor placed on the masonry interior without inclusion of a “leaky” mortar joint. Simultaneously, the conservative approach underestimated drying experienced by the relative humidity sensor in two of three experiment wall segments. Regarding beam-end moisture content, the modeling approach conservatively enveloped experiment results in 3D but not in 2D.

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Green thermal insulators: A review into the role of biopolymer‐based aerogels in thermal insulation applications

Giuma,

Khalil,

Yahya

et al. 2024

Polymer Engineering & Sci

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The need for green thermal insulation materials, such as biopolymer aerogels, has become increasingly critical in the face of escalating environmental concerns and the urgent push toward sustainable practices. The unique characteristics of biopolymer aerogels, coupled with their environmental benefits, position them as potential disruptors in the insulation industry. As research continues, addressing challenges and refining fabrication techniques will likely lead to wider adoption of these materials, contributing to a greener and more energy‐efficient built environment. This review presents the latest developments concerning the properties and versatile applications of biopolymer‐based thermal insulators as a new type of green materials. It comprehensively examines the fundamental principles of thermal insulation, factors that influence its efficacy, and the compatibility and mechanisms underlying bioaerogels within this context. The review also addresses the latest works about the utilization of different biopolymer aerogels in different thermal insulation applications and critically assesses the obstacles currently faced by biopolymer‐based aerogels and elucidates potential avenues for future advancement.Highlights Biopolymer aerogels offer a sustainable alternative in insulation. Challenges in production limit current aerogel adoption rates. Latest advancements highlight aerogels' versatile insulation applications. Future research aims to enhance biopolymer aerogel technology and use.

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Modelling hydraulic conductivity for porous building materials based on a prediction of capillary conductivity at capillary saturation

Cited by 12 publications

References 33 publications

Water-vapour permeability of inorganic construction materials

Water-vapour permeability of inorganic construction materials

Hygrothermal Simulation of Interior Insulated Brick Wall—Perspectives on Uncertainty and Sensitivity

Green thermal insulators: A review into the role of biopolymer‐based aerogels in thermal insulation applications

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