scholarly journals Research of Wood Waste as a Potential Filler for Loose-Fill Building Insulation: Appropriate Selection and Incorporation into Polyurethane Biocomposite Foams

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5336
Author(s):  
Nerijus Augaitis ◽  
Saulius Vaitkus ◽  
Sylwia Członka ◽  
Agnė Kairytė
Keyword(s):  
Thermal Conductivity ◽  
Water Absorption ◽  
Water Vapour ◽  
Wood Waste ◽  
Diffusion Resistance ◽  
Water Vapour Diffusion ◽  
Recycling Potential ◽  
Water Vapour Resistance ◽  
The Stability ◽  
Loose Fill

Currently, the recycling potential of wood waste (WW) is still limited, and in a resource efficiency approach, recycling WW in insulation materials, such as polyurethane (PUR), appears as an appropriate solution. It is known that the quality of WW is the main aspect which influences the stability of the final products. Therefore, the current study analyses different WW-based fillers as possible modifiers for polyurethane biocomposite foams for the application as loose-fill materials in building envelopes. During the study of WW-based fillers, it was determined that the most promising filler is wood scobs (WS) with a thermal conductivity of 0.0496 W/m·K, short-term water absorption by partial immersion—12.5 kg/m2, water vapour resistance—0.34 m2·h·Pa/mg and water vapour diffusion resistance factor—2.4. In order to evaluate the WS performance as a filler in PUR biocomposite foams, different ratios of PUR binder and WS filler (PURb/WS) were selected. It was found that a 0.40 PURb/WS ratio is insufficient for the appropriate wetting of WS filler while a 0.70 PURb/WS ratio produced PUR biocomposite foams with the most suitable performance: thermal conductivity reduced from 0.0523 to 0.0476 W/m·K, water absorption—from 5.6 to 1.3 kg/m2, while the compressive strength increased from 142 to 272 kPa and the tensile strength increased from 44 to 272 kPa.

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.

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.

scholarly journals Determination of thermal conductivity of moist rigid polymer foams

2019 ◽  
Vol 282 ◽  
pp. 02021
Author(s):  
Vadzim Nikitsin ◽  
Abdrahman Alsabry ◽  
Beata Backiel-Brzozowska ◽  
Valery Kofanov
Keyword(s):  
Thermal Conductivity ◽  
Water Vapour ◽  
Pore Space ◽  
Geometric Model ◽  
Effective Porosity ◽  
Pore Surface ◽  
Polymer Foam ◽  
Rigid Polymer ◽  
Water Vapour Diffusion ◽  
Calculation Results

A geometric model of the polymer foam structure was verified taking into account the moisture content of the material and the degree of wetness of the pore surface. Mathematical relations were developed to determine the moisture value at which transition from partial to full wetting of the pore surface occurs and vice versa. A mathematical description of the heat transport process was carried out in the model structure of moist foam taking into account the diffusion of water vapour in the pore space and the nature of wetting of the pore surface. The influence of material porosity, its moisture and water vapour diffusion within the effective porosity on the effective thermal conductivity of the material was determined by calculation. A comparison between the calculation results and experimental data shows their sufficient compatibility.

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 The Effect of Cement Addition on Water Vapour Resistance Factor of Rammed Earth

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2249
Author(s):  
Piotr Narloch ◽  
Wojciech Piątkiewicz ◽  
Barbara Pietruszka
Keyword(s):  
Water Vapour ◽  
Construction Materials ◽  
Resistance Factor ◽  
Soil Particle ◽  
Rammed Earth ◽  
Diffusion Resistance ◽  
Particle Sizes ◽  
Literature Analysis ◽  
Test Results ◽  
Water Vapour Resistance

The article aims to determine the effect of cement addition on the water vapour resistance factor of stabilized rammed earth. Literature analysis indicates that different earthen materials show large differences in water vapour resistance factor values. The high diffusion resistance of concrete concerning other construction materials suggests that cement will be one of the factors significantly affecting these values. The paper presents water vapour resistance factor test results of rammed earth with various soil particle sizes and cement contents. The obtained results showed that an increase of cement addition increases the diffusion resistance of the material. However, the diffusion resistance of cement stabilized rammed earth is still low compared to concrete.

scholarly journals Influence of production on hemp concrete hygrothermal properties: sorption, water vapour permeability and water absorption

2021 ◽  
Vol 2069 (1) ◽  
pp. 012004
Author(s):  
A Ruus ◽  
T Koosapoeg ◽  
M Pau ◽  
T Kalamees ◽  
M Põldaru
Keyword(s):  
Thermal Conductivity ◽  
Water Absorption ◽  
Water Vapour ◽  
Thermal Insulation ◽  
Building Material ◽  
Water Vapour Permeability ◽  
Wall Material ◽  
Vapour Permeability ◽  
Water Vapour Sorption ◽  
Negative Material

Abstract Hemp concrete is considered to be a carbon negative material. Hemp absorbs CO2 during the growth and lime needs CO2 for carbonation. The material, which has good thermal insulation properties, is used as a non-bearing wall material or plaster. For such use the hygrothermal properties of a material must be well known especially when indoor insulation is in focus. In the current study hemp concrete produced in two different ways was in focus and following the hygrothermal properties of hemp concrete as a building material were studied: water absorption (EN 1015-18), water vapour sorption (EN 12571), water vapour permeability (EN 12572) and thermal conductivity (EN 12667). The results of the study can be used in hygrotheramal calculations and modelling.

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