Determination of Hygric Properties of Hollow Brick Block as a Function of Moisture Content

2014 ◽  
Vol 982 ◽  
pp. 54-58
Author(s):  
Tomáš Korecký ◽  
Miloš Jerman ◽  
Robert Černý
Keyword(s):  
Adsorption Isotherm ◽  
Moisture Content ◽  
Water Vapour ◽  
Moisture Diffusivity ◽  
Diffusion Resistance ◽  
Water Vapour Diffusion ◽  
Vapour Diffusion ◽  
Hollow Brick ◽  
Hygric Properties

In the paper is presented calculation of hygric properties of hollow brick block. Namely it is adsorption isotherm, water vapour diffusion resistance factor and moisture diffusivity. The brick block cavities was filled only by air. In first step the properties of brick body were measured. Then the properties of the whole brick block were calculated by using homogenisation techniques.

Untersuchungen zum Diffusionswiderstand von Holzwerkstoffen | Diffusion resistance of timber materials

2005 ◽  
Vol 156 (3-4) ◽  
pp. 100-103
Author(s):  
Rudolf Popper ◽  
Peter Niemz ◽  
Gerhild Eberle
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Middle Lamella ◽  
Solid Wood ◽  
Diffusion Resistance ◽  
Water Vapour Diffusion ◽  
Wood Panels ◽  
Vapour Diffusion ◽  
Wet Climate ◽  
Panel Thickness

The water vapour diffusion resistance of timber materials were tested in a wet climate (relative humidity ranging from 100%to 65% at 20 °C) and in a dry climate (relative humidity ranging from 0% to 65% and from 0% to 35% at 20 °c) with variation by relative humidity and vapour pressure gradient. The diffusion resistance of multilayer solid wood panels lies under or within the range of the solid wood (spruce), tending even to a lower range. This can be attributed to the loosely inserted middle lamella of the used solid wood panels, which were not correctly glued by the manufacturer. The diffusion resistance of the solid wood panels increases with decreasing moisture content and decreasing panel thickness, as well as with increasing water vapour gradient from 818 to 1520 Pa. There were clear differences between the tested timber materials. The diffusion resistance of particle composites is strongly dependent on the specific gravity. Due to laminar particles OSBs(Oriented Strand Boards) have a larger diffusion resistance than chipboards. The water vapour diffusion resistance of OSBs lies within the range of plywood.

Effects of exposure on water relations and photosynthesis of western hemlock in habitat forms

1976 ◽  
Vol 6 (1) ◽  
pp. 40-48 ◽  
Author(s):  
R. A. Keller ◽  
E. B. Tregunna
Keyword(s):  
Light Intensity ◽  
Water Content ◽  
Water Vapour ◽  
Western Hemlock ◽  
Diffusion Resistance ◽  
The Sun ◽  
Evaporative Demand ◽  
Photosynthetic Rates ◽  
Water Vapour Diffusion ◽  
Vapour Diffusion

Measurements of relative turgidity, transpiration rates, and photosynthetic rates on sun-grown and shade-grown western hemlock (Tsugaheterophylla (Raf.) Sarg.) were used to indicate effects of varying degrees of exposure.The sun-adapted form had low photosynthetic rates but maintained its water content under conditions of high evaporative demand. The shade-adapted form desiccated under exposed conditions, and in contrast with the sun-adapted form, its water vapour diffusion resistance decreased with increasing light intensity.

Hygric Properties of HPC with Natural Pozzolana

2016 ◽  
Vol 677 ◽  
pp. 93-97 ◽  
Author(s):  
Jaroslava Koťátková ◽  
Monika Čáchová ◽  
Dana Koňáková ◽  
Eva Vejmelková
Keyword(s):  
Water Vapour ◽  
High Performance ◽  
High Performance Concrete ◽  
Diffusion Resistance ◽  
Supplementary Cementitious Material ◽  
Water Vapour Transport ◽  
Water Vapour Diffusion ◽  
Natural Pozzolana ◽  
Vapour Diffusion ◽  
Liquid Water Transport

The water vapour transport and the liquid water transport of high performance concrete (HPC) with the content of natural pozzolana are the described in this paper. Studied properties are presented by means of water vapour diffusion coefficient, water vapour diffusion resistance factor and absorption coefficient respectively. The natural pozzolana (NP), namely natural zeolite, is used as supplementary cementitious material which affects the durability properties of the end product. The obtained results revealed the effectiveness of NP in the terms of both studied properties when used in small amounts, i.e. at about 20% of cement weight. On the other hand substitutions higher than 40% result in worsening of the resistance of the concrete to water and water vapour ingress and its movement trough the material.

Measuring of Equivalent Air Layer Thickness of Nanofibre Textiles

2016 ◽  
Vol 714 ◽  
pp. 192-195 ◽  
Author(s):  
Martin Černohorský ◽  
Petr Semerák ◽  
Petra Tichá
Keyword(s):  
Layer Thickness ◽  
Water Vapour ◽  
Measurement Method ◽  
Measurement Methods ◽  
Diffusion Resistance ◽  
Sheet Materials ◽  
Water Vapour Diffusion ◽  
Vapour Diffusion ◽  
Method Of Measurement ◽  
Open Materials

This article deals with selecting the appropriate method of measurement water vapour diffusion through nanofibre textiles. Parameter for comparison of different sheet materials for its ability to brake the water vapour is a equivalent air layer thickness value Sd. The equivalent air layer thickness Sd [m] expresses the equivalent air layer thickness of the air layer, which would have the same diffusion resistance as the thickness of the measured material. It is necessary to choose the appropriate measurement method for determining the value Sd with diffusion open materials such as nanofibre materials. This article compares the outcomes of two measurement methods – Dry Cup Method and Tube Method. The measurements were carried out on a sample from nanofibre textiles based on PVDF.

scholarly journals Water vapour diffusion resistance factor of Phyllostachys edulis (Moso bamboo)

2017 ◽  
Vol 141 ◽  
pp. 216-221 ◽  
Author(s):  
Puxi Huang ◽  
Eshrar Latif ◽  
Wen-Shao Chang ◽  
Martin P. Ansell ◽  
Mike Lawrence
Keyword(s):  
Water Vapour ◽  
Resistance Factor ◽  
Moso Bamboo ◽  
Diffusion Resistance ◽  
Phyllostachys Edulis ◽  
Water Vapour Diffusion ◽  
Vapour Diffusion

scholarly journals Combined bound water and water vapour diffusion of Norway spruce and European beech in and between the principal anatomical directions

Holzforschung ◽  
2011 ◽  
Vol 65 (6) ◽  
pp. 819-828 ◽  
Author(s):  
Walter Sonderegger ◽  
Manuele Vecellio ◽  
Pascal Zwicker ◽  
Peter Niemz
Keyword(s):  
Diffusion Coefficient ◽  
Steady State ◽  
Water Vapour ◽  
Diffusion Coefficients ◽  
Bound Water ◽  
European Beech ◽  
Unsteady State ◽  
Water Vapour Diffusion ◽  
Vapour Diffusion ◽  
Water Vapour Resistance

Abstract The combined bound water and water vapour diffusion of wood is of great interest in the field of building physics. Due to swelling stresses, the steady-state-determined diffusion coefficient clearly differs from the unsteady-state-determined diffusion coefficient. In this study, both diffusion coefficients and the water vapour resistance factor of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) were investigated for the principal anatomical directions (radial, tangential and longitudinal) and in 15° steps between these directions. The values were determined with the cup method as the basic principle. The unsteady-state-determined diffusion coefficient is, independent of the direction, about half that of the steady-state-determined diffusion coefficient. Both diffusion coefficients are about two to three times higher for spruce than for beech. They are up to 12 times higher in the longitudinal direction than perpendicular to the grain for spruce, and up to 15 times higher for beech. With increasing moisture content, the diffusion coefficients exponentially increase. The water vapour resistance factor shows converse values to the diffusion coefficients.

Condensation of Water Vapour in the Functional Gap of Window - Experimental Measurement of Exfiltration at 15 Pa

2016 ◽  
Vol 820 ◽  
pp. 285-292
Author(s):  
Adela Palková ◽  
Ľuboš Kamenický ◽  
Milan Palko
Keyword(s):  
Heat Transfer ◽  
Water Vapour ◽  
Experimental Measurement ◽  
Experimental Analysis ◽  
Experimental Measurements ◽  
Air Filtration ◽  
Climatic Chamber ◽  
University Of Technology ◽  
Water Vapour Diffusion ◽  
Vapour Diffusion

The article is focused on the experimental analysis of water vapour in functional gap of wooden window. The experimental measurements were held in a laboratory of heat engineering of the Slovak university of Technology in Bratislava – in a big climatic chamber for synergic phenomena of heat transfer, water vapour diffusion and air filtration.

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