ASTM D7178-16e1

Standard Practice for Determining the Number of Constrictions &#x201c;<emph type="bdit" >m</emph>&#x201d; of Non-Woven Geotextiles as a Complementary Filtration Property

SIGNIFICANCE AND USE
5.1 This practice provides a calculation method for determining the number of constrictions m of a non-woven geotextile (or of a layer of a composite material). This standard is not applicable to woven geotextiles, knitted geotextiles, heat-bonded geotextiles or any other type of geosynthetic.  
5.2 The number of constriction represents the number of “windows” delimited by three or more fibers, in which soil particles could migrate. In that regard, it can be basically defined by the following equation:  where t is the thickness and dc the average distance between two constrictions. This value has been found to be relevant to explain the different filtration behaviors of non-woven geotextiles with similar opening sizes but different structures for various soil conditions (see Appendix X1 for details).  
5.3 This value will be used in filtration research to evaluate the prediction of filtration efficiency and effectiveness of various non-woven geotextiles with similar opening sizes (Test Method D6767).  
5.4 Interpretation of the significance of m as calculated using this standard shall be done with care as some non-woven structures may not reflect the hypothesis used to establish the proposed equation (see Appendix X1 for details).
SCOPE
1.1 This practice describes the procedure used along with existing test method to determine the number of constrictions  m of mechanically bonded non-woven geotextiles, based on thickness, mass per unit area and fiber properties  
1.2 The number of constrictions is a property of non-woven geotextiles, which is complementary to opening size to predict their filtration behavior. It can be used to differentiate non-woven geotextiles with similar opening sizes but different structures (thickness, weight, fiber diameter, etc.). However, more research is needed to assess its significance when comparing two products with different opening sizes.  
1.3 Consideration of the number of constriction is relevant in filtration applications where piping or clogging concerns are to be controlled with a high level of confidence, that is, for filters applications in critical soils.  
1.4 This standard is for design purposes only and is not intended for quality control purposes.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-May-2016
• ICS: 59.080.70 - Geotextiles
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.03 - Permeability and Filtration

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
´1
Designation: D7178 − 16
Standard Practice for
Determining the Number of Constrictions “m” of Non-
1
Woven Geotextiles as a Complementary Filtration Property
This standard is issued under the fixed designation D7178; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
ε NOTE—A legend was added editorially to Eq X1.4 in X1.1.2.2 in July 2016.
1. Scope D5199 Test Method for Measuring the Nominal Thickness
of Geosynthetics
1.1 This practice describes the procedure used along with
D5261 Test Method for Measuring Mass per Unit Area of
existing test method to determine the number of constrictions
Geotextiles
m of mechanically bonded non-woven geotextiles, based on
D6767 Test Method for Pore Size Characteristics of Geotex-
thickness, mass per unit area and fiber properties
tiles by Capillary Flow Test
1.2 The number of constrictions is a property of non-woven
geotextiles, which is complementary to opening size to predict
3. Terminology
their filtration behavior. It can be used to differentiate non-
3.1 Definitions—For definitions of terms used in this test
woven geotextiles with similar opening sizes but different
method, refer to Terminology D4439.
structures (thickness, weight, fiber diameter, etc.). However,
more research is needed to assess its significance when
3.2 Definitions of Terms Specific to This Standard:
comparing two products with different opening sizes.
3.2.1 constriction—in the non-woven geotextile, a “win-
dow” delimited by three or more fibers, through which soil
1.3 Consideration of the number of constriction is relevant
particles could migrate.
in filtration applications where piping or clogging concerns are
to be controlled with a high level of confidence, that is, for
3.2.2 filtration paths—under the forces induced by fluid
filters applications in critical soils.
flows, soil particles may travel in the geotextile filter along
filtration paths. Each of these paths is composed of a sequence
1.4 This standard is for design purposes only and is not
of constrictions of various size and shape.
intended for quality control purposes.
3.2.3 number of constrictions, m—average number of con-
1.5 This standard does not purport to address all of the
strictions for a filtration path.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.2.4 fiber count, T—a measure of the linear density of the
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priate safety and health practices and determine the applica-
fiber expressed in tex, where 1 tex = 10 kg/m.
bility of regulatory limitations prior to use.
3.2.4.1 Discussion—The fiber count is sometime expressed
in “Denier” (equivalent to the weight in grams of a theoretical
2. Referenced Documents
9000 meters long fiber). The value in “Tex” can be obtained
2
2.1 ASTM Standards:
from the value in Denier considering that 1 Denier = 9 Tex.
D1577 Test Methods for Linear Density of Textile Fibers
3.2.5 opening size—largest significant opening of a non-
D4439 Terminology for Geosynthetics
woven geotextile as measured using Test Method D6767.
D4751 Test Method for DeterminingApparent Opening Size
of a Geotextile NOTE 1—Although Test Method D4751 (Apparent Opening Size) is
widely used to characterize geotextiles, it may often not be sufficient for
advanced filtration investigations such as those requiring consideration of
1
This practice is under the jurisdiction of ASTM Committee D35 on Geosyn-
the number of constriction as a significant parameter. The “bubble-point”
thetics and is the direct responsibility of Subcommittee D35.03 on Permeability and
measurement technique proposed in Test Method D6767 shall thus be
Filtration.
preferred to AOS per Test Method D4751.
Current edition approved June 1, 2016. Published June 2016. Originally
published 2006. Last previous version approved 2011 as D7178 – 06 (2011). DOI:
4. Summary of Practice
10.1520/D7178-16E01.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.1 The physical properties of the geotextile are evaluated
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
accordingtospecificproceduresandthenumberofconstriction
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. m is determined based on Eq 1.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
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D7178 − 16
5. Significance and Use 6.3.1 Calculate the number of constrictions m of the geo-
textile using Eq 1 (dimensionless value). Result must be
5
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: D7178 − 16 D7178 − 16
Standard Practice for
Determining the Number of Constrictions “m” of Non-
1
Woven Geotextiles as a Complementary Filtration Property
This standard is issued under the fixed designation D7178; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
ε NOTE—A legend was added editorially to Eq X1.4 in X1.1.2.2 in July 2016.
1. Scope
1.1 This practice describes the procedure used along with existing test method to determine the number of constrictions m of
mechanically bonded non-woven geotextiles, based on thickness, mass per unit area and fiber properties
1.2 The number of constrictions is a property of non-woven geotextiles, which is complementary to opening size to predict their
filtration behavior. It can be used to differentiate non-woven geotextiles with similar opening sizes but different structures
(thickness, weight, fiber diameter, etc.). However, more research is needed to assess its significance when comparing two products
with different opening sizes.
1.3 Consideration of the number of constriction is relevant in filtration applications where piping or clogging concerns are to
be controlled with a high level of confidence, that is, for filters applications in critical soils.
1.4 This standard is for design purposes only and is not intended for quality control purposes.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
D1577 Test Methods for Linear Density of Textile Fibers
D4439 Terminology for Geosynthetics
D4751 Test Method for Determining Apparent Opening Size of a Geotextile
D5199 Test Method for Measuring the Nominal Thickness of Geosynthetics
D5261 Test Method for Measuring Mass per Unit Area of Geotextiles
D6767 Test Method for Pore Size Characteristics of Geotextiles by Capillary Flow Test
3. Terminology
3.1 Definitions—For definitions of terms used in this test method, refer to Terminology D4439.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 constriction—in the non-woven geotextile, a “window” delimited by three or more fibers, through which soil particles
could migrate.
3.2.2 filtration paths—under the forces induced by fluid flows, soil particles may travel in the geotextile filter along filtration
paths. Each of these paths is composed of a sequence of constrictions of various size and shape.
3.2.3 number of constrictions, m—average number of constrictions for a filtration path.
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3.2.4 fiber count, T—a measure of the linear density of the fiber expressed in tex, where 1 tex = 10 kg/m.
1
This practice is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.03 on Permeability and Filtration.
Current edition approved June 1, 2016. Published June 2016. Originally published 2006. Last previous version approved 2011 as D7178 – 06 (2011). DOI:
10.1520/D7178-16.10.1520/D7178-16E01.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3.2.4.1 Discussion—
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7178 − 16
The fiber count is sometime expressed in “Denier” (equivalent to the weight in grams of a theoretical 9000 meters long fiber). The
value in “Tex” can be obtained from the value in Denier considering that 1 Denier = 9 Tex.
3.2.5 opening size—largest significant opening of a non-woven geotextile as measured using Test Method D6767.
NOTE 1—Although Test Method D4751 (Apparent Opening Size) is widely used to characterize geotextiles, it may often not be sufficient for advanced
filtration investigations such as those requiring consideration of the number of constriction as a significant parameter. The “bubble-point” measurement
technique proposed in Test Method D6767 shall thus be preferred to AOS per Test Method D4751.
4. Summary of
...