Air Permeability Measurement

1988 ◽  
Vol 137 ◽  
Author(s):  
Daniel Perraton ◽  
André Carles-Gibergues ◽  
Pierre-Claude Aitcin ◽  
Bernard Thenoz
Keyword(s):  
Permeability Coefficient ◽  
Room Temperature ◽  
Air Permeability ◽  
Permeability Test ◽  
Permeability Measurement ◽  
Permeability Coefficients ◽  
Corrected Equation ◽  
Variable Porosity ◽  
Margin Of Error ◽  
The Difference

AbstractAir permeability was determined for concretes of variable porosity (w/c ratio of 0.33, 0.50, and 0.67). The reproducibility of the test and the ability to characterize the permeability of different concrete were evaluated. Results indicate that air permeability test gives suitable reproducibility with a margin of error of 10%, which tends to improve with increase in w/c ratio. The difference in air permeability of concretes with the w/c ratios investigated are distinguishable by this technique. Furthermore air permeability coefficients used were modified with equations derived in accordance to Darcy's law, and the resulting air permeabilities compared. Data calculated with an air permeability coefficient based on mean radius pore (corrected equation) appears to give a more realistic value with greater differentiation between the ranges. Values were determined on specimens after 28 days, maintained at room temperature (50% RH), then again after an additional 2 days at 60°C in a ventilated oven. Oven-dried specimens exhibit significantly greater air permeability.

scholarly journals Correlations between Air Permeability Coefficients and Pore Structure Indicators of Cementitious Materials

2018 ◽  
Author(s):  
Yuya Sakai
Keyword(s):  
Pore Structure ◽  
Pore Volume ◽  
Percolation Theory ◽  
Permeability Coefficient ◽  
Pore Diameter ◽  
Total Pore Volume ◽  
Cementitious Materials ◽  
Air Permeability ◽  
Permeability Coefficients ◽  
Using Data

Correlations between the air permeability coefficient and various pore structure indicators in cementitious materials were examined to determine the pore structure indicator that best evaluated air permeability using data from previous studies of air permeabilities and pore structures. The determination coefficients of air permeability with total pore volume, critical pore diameter, and ordinary threshold pore diameter were low, although these have often been used as indicators. The median and threshold pore diameters obtained by percolation theory showed high determination coefficients. The equation using the threshold pore diameter better estimated the air permeability coefficient than the Katz–Thompson equation.

Effect of titanium alloys elasticity modulus on warping of stamped blanks during cooling

2021 ◽  
pp. 221-227
Author(s):  
M.O. Smirnov ◽  
A.M. Zolotov ◽  
A.M. Tyukhtyaev
Keyword(s):  
Mathematical Modeling ◽  
Titanium Alloys ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Elasticity Modulus ◽  
Preliminary Deformation ◽  
Wide Spread ◽  
Temperature Dependences ◽  
Cumulative Deformation ◽  
The Difference

Wide spread in the values of the elasticity modulus of the titanium VT6 alloy and its analogs Ti—6Al—4V, Ti—6Al—4V ELI at room temperature and at elevated temperatures is revealed аs result of the literature sources analysis. The data are ambiguous, the available temperature dependences of the elasticity modulus have very different values starting from the temperature T l 500 °C. Mathematical modeling of the warping process is carried out on the example of figurine-shaped stamped blank of turbine blade using various dependences of the elasticity modulus on temperature. Cases of warping during cooling of stamped blank after cooling-down in stamp with and without cumulative deformation are considered. The difference in the course of thermal deformations during the cooling of the workpiece is obtained using different temperature dependences of the elasticity modulus. The presence of preliminary deformation increases the warping of the workpieces.

The air permeability of composite fiber material

2021 ◽  
Vol 1 ◽  
pp. 42-48
Author(s):  
T. A. Leshchenko ◽  
◽  
N. V. Chernousova ◽  
A. V. Dedov ◽  
◽  
...  
Keyword(s):  
Composite Materials ◽  
Permeability Coefficient ◽  
Pore Space ◽  
Fiber Material ◽  
Composite Fiber ◽  
Air Permeability ◽  
Rubber Content ◽  
Limited Mobility ◽  
Fibrous Matrix ◽  
Composite Fiber Material

The air permeability of composite materials obtained by impregnating a non-woven needle-punched cloth with latex was investigated. The permeability of composite materials with different rubber content was estimated by the coefficient of air permeability at a pressure drop of 49 and 100 Pa. The dependence of the air permeability coefficient on the degree of impregnation of the fabric showed that at 15 – 20 % of the rubber content, the maximum air permeability coefficient is observed, and when the degree of impregnation increases, the air permeability coefficient decreases. The process of forming a porous structure of composite materials and its influence on air transport is considered. The increase of the coefficient of permeability is explained by the fixation of the fibers of the surface layer with limited mobility under the action of air flow, and a reduction in the coefficient of air permeability by reducing pore space and an increase in fiber matrix composite materials in the process of sushi-Ki-impregnated material. The air permeability of composite materials is determined by the ratio between the processes of increasing the volume of the fibrous matrix and reducing porosity when filling the space between the portages with rubber particles. A model is proposed for calculating the coefficient of breathability of composite materials of known density.

scholarly journals Storage and Condition of Biomass Influence to Biosorption of Lead (II) and Zinc(II) by Saccharomyces cerevisiae Biomass

2010 ◽  
Vol 1 (1) ◽  
pp. 11-15
Author(s):  
Jasmidi Jasmidi ◽  
Eko Sugiharto ◽  
Mudjiran Mudjiran
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Atomic Absorption ◽  
Room Temperature ◽  
Final Concentration ◽  
Biomass Storage ◽  
Lead And Zinc ◽  
The Difference ◽  
Biomass Influence ◽  
And Storage ◽  
Zinc Storage

The influence of length and condition of Biomass Storage on the biosorption of lead and zinc that present together in a solution by Saccharomyces cerevisiae biomass were studied. In this experiment, variables of length and condition of biomass storage were examined. Concentration of lead and zinc were determined by atomic absorption spectrophotometric (AAS) using air-acetilene as atomizing flame. Loading of lead and zinc on the biomass were determined as the difference between the initial and the final concentration of lead and zinc in the solution. Biosorption of lead and zinc were influenced by condition and storage of the biomass. Storage of biomass in the room temperature for one week cause an increasing uptake. Storage for longer period result in decrease of lead and zinc uptake. Storage of biomass in a freezer up to 2 weeks increased the uptake of lead, but did not influence the uptake of zinc. Storage for longer period decreased the uptake of both of lead and zinc. For all condition the uptake of lead higher than the uptake of zinc by Saccharomyces cerevisiae.

scholarly journals The principal magnetic susceptibilities of neodymium sulphate octahydrate at low temperatures

1939 ◽  
Vol 170 (941) ◽  
pp. 266-271 ◽  
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Energy Levels ◽  
Constant Factor ◽  
The Other ◽  
Crystalline Field ◽  
Cubic Symmetry ◽  
The Subject ◽  
The Difference ◽  
The One

The magnetic and other related properties of neodymium sulphate have been the subject of numerous investigations in recent years, but there is still a remarkable conflict of evidence on all the essential points. The two available determinations of the susceptibility of the powdered salt at low temperatures, those of Gorter and de Haas (1931) from 290 to 14° K and of Selwood (1933) from 343 to 83° K both fit the expression X ( T + 45) = constant over the range of temperature common to both, but the constants are not the same and the susceptibilities at room temperature differ by 11%. The fact that the two sets of results can be converted the one into the other by multiplying throughout by a constant factor suggested that the difference in the observed susceptibilities was due to some error of calibration. It could, however, also be due to the different purity of the samples examined though the explanation of the occurrence of the constant factor is then by no means obvious. From their analysis of the absorption spectrum of crystals of neodymium sulphate octahydrate Spedding and others (1937) conclude that the crystalline field around the Nd+++ ion is predominantly cubic in character since they find three energy levels at 0, 77 and 260 cm. -1 .* Calculations of the susceptibility from these levels reproduce Selwood’s value at room temperature but give no agreement with the observations-at other temperatures. On the other hand, Penney and Schlapp (1932) have shown that Gorter and de Haas’s results fit well on the curve calculated for a crystalline field of cubic symmetry and such a strength that the resultant three levels lie at 0, 238 and 834 cm. -1 , an overall spacing almost three times as great as Spedding’s.

scholarly journals Kenaf Fibre Reinforced Polypropylene Composites: Effect of Cyclic Immersion on Tensile Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
W. H. Haniffah ◽  
S. M. Sapuan ◽  
K. Abdan ◽  
M. Khalid ◽  
M. Hasan ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Tensile Properties ◽  
Room Temperature ◽  
Tap Water ◽  
Tensile Modulus ◽  
Polypropylene Composites ◽  
Preliminary Results ◽  
Kenaf Fibre ◽  
The Difference ◽  
Number Of Cycles

This research studied the degradation of tensile properties of kenaf fibre reinforced polypropylene composites due to cyclic immersion into two different solutions, as well as comparison of the developed composites’ tensile properties under continuous and cyclic immersion. Composites with 40% and 60% fibre loadings were immersed in tap water and bleach for 4 cycles. Each cycle consisted of 3 days of immersion and 4 days of conditioning in room temperature (28°C and 55% humidity). The tensile strength and modulus of composites were affected by fibre composition, type of liquid of immersion, and number of cycles. The number of immersion cycles and conditioning caused degradation to tensile strength and modulus of kenaf fibre reinforced polypropylene composites. Continuous and cyclic immersion in bleach caused tensile strength of the composites to differ significantly whereas, for tensile modulus, the difference was insignificant in any immersion and fibre loadings. However, continuous immersion in the bleach reduced the tensile strength of composites more compared to cyclic immersion. These preliminary results suggest further evaluation of the suitability of kenaf fibre reinforced polypropylene composites for potential bathroom application where the composites will be exposed to water/liquid in cyclic manner due to discontinuous usage of bathroom.

Sign in / Sign up

Export Citation Format

Share Document