ASTM D5323-92(2018)
(Practice)Standard Practice for Determination of 2 % Secant Modulus for Polyethylene Geomembranes
Standard Practice for Determination of 2 % Secant Modulus for Polyethylene Geomembranes
SIGNIFICANCE AND USE
4.1 Where to draw the tangent to determine the modulus of elasticity is often unclear when performing tensile tests with polyethylene geomembranes. This problem results in a wide variation in test results and, therefore, makes this property unreliable for comparisons.
4.2 A secant modulus based on 2 % strain can be useful when making comparisons between materials, in quality control, and in comparing the same sample after being subjected to a nonstandard environment.
4.3 Secant modulus is an approximation of modulus of elasticity and generally results in a lower value than that for the modulus of elasticity.
4.4 Although the technique for measuring 2 % secant modulus is described here, other percent secant moduli can be measured by this practice.
SCOPE
1.1 This practice presents a technique for calculating the 2 % secant modulus for polyethylene geomembranes between 0.5 and 5 mm (20 and 200 mil) using Test Method D638.
1.2 This practice will facilitate modulus comparisons of similar materials by standardizing the method for deriving the points on the stress-strain curve from which the calculations are performed.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D5323 − 92 (Reapproved 2018)
Standard Practice for
Determination of 2 % Secant Modulus for Polyethylene
Geomembranes
This standard is issued under the fixed designation D5323; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1.1 Discussion—The stress-strain relations of many
plastics do not conform to Hooke’s law throughout the elastic
1.1 This practice presents a technique for calculating the
range, but rather deviate therefrom even at strains well below
2% secant modulus for polyethylene geomembranes between
the elastic limit. For such materials, the slope of the tangent to
0.5 and 5 mm (20 and 200 mil) using Test Method D638.
the stress-strain curve at a low strain is usually taken as the
1.2 This practice will facilitate modulus comparisons of
modulus of elasticity (or elastic modulus). Since the existence
similar materials by standardizing the method for deriving the
ofatrueproportionallimitinpolyethyleneisquestionable,and
points on the stress-strain curve from which the calculations
with the impracticality of measuring it reliably, the use of
are performed.
secant modulus for comparative evaluations is preferred.
1.3 The values stated in SI units are to be regarded as
3.1.2 secant modulus, n—the ratio of stress (nominal) to
standard. The values given in parentheses are for information
corresponding strain at any specified point on the stress-strain
only.
curve.
1.4 This standard does not purport to address all of the
3.1.2.1 Discussion—The measurement units for secant
safety concerns, if any, associated with its use. It is the
modulus may change, depending on the standard used. For the
responsibility of the user of this standard to establish appro-
purposes of this practice, the measurement units shall be force
−2
priate safety, health, and environmental practices and deter-
per unit area (FL ), such as megapascals (pounds-force per
mine the applicability of regulatory limitations prior to use.
square inch).
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Significance and Use
ization established in the Decision on Principles for the
4.1 Where to draw the tangent to determine the modulus of
Development of International Standards, Guides and Recom-
elasticity is often unclear when performing tensile tests with
mendations issued by the World Trade Organization Technical
polyethylene geomembranes. This problem results in a wide
Barriers to Trade (TBT) Committee.
variation in test results and, therefore, makes this property
2. Referenced Documents unreliable for comparisons.
2.1 ASTM Standards:
4.2 A secant modulus based on 2% strain can be useful
D638Test Method for Tensile Properties of Plastics
when making comparisons between materials, in quality
control, and in comparing the same sample after being sub-
3. Terminology
jected to a nonstandard environment.
3.1 Definitions:
4.3 Secant modulus is an approximation of modulus of
−2
3.1.1 modulus of elasticity, MPa (FL ), n—the ratio of
elasticityandgenerallyresultsinalowervaluethanthatforthe
stress(nominal)tocorrespondingstrainbelowtheproportional
modulus of elasticity.
limit of a material, expressed in force per unit area, such as
4.4 Althoughthetechniqueformeasuring2%secantmodu-
megapascals (pounds-force per square inch).
lus is described here, other percent secant moduli can be
measured by this practice.
This practice is under the jurisdiction of ASTM Committee D35 on Geosyn-
thetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.
CurrenteditionapprovedJuly1,2018.PublishedJuly2018.Originallyapproved
5. Procedure
in 1992. Last previous edition approved in 2011 as D5323–92 (2011). DOI:
10.1520/D5323-92R18. 5.1 Follow the test procedure described in Test Method
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
D638.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.1.1 A crosshead speed of 50 mm/min (2 ipm) is recom-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. mendedfordeterminingsecantmodulus,regardlessofthetype
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5323 − 92 (2018)
of geomembrane being evaluated. Faster crosshead speeds 5.3 Calculate the 2% secant modulus as follows:
reduce resolution of the points
...
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.
Designation: D5323 − 92 (Reapproved 2011) D5323 − 92 (Reapproved 2018)
Standard Practice for
Determination of 2 % Secant Modulus for Polyethylene
Geomembranes
This standard is issued under the fixed designation D5323; 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. Scope
1.1 This practice presents a technique for calculating the 2 % secant modulus for polyethylene geomembranes between 0.5 and
5 mm (20 and 200 mil) using Test Method D638.
1.2 This practice will facilitate modulus comparisons of similar materials by standardizing the method for deriving the points
on the stress-strain curve from which the calculations are performed.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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 consult and establish appropriate safety safety, health, and healthenvironmental practices and
determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D638 Test Method for Tensile Properties of Plastics
3. Terminology
3.1 Definitions:
−2
3.1.1 modulus of elasticity, MPa (FL ), n—the ratio of stress (nominal) to corresponding strain below the proportional limit
of a material, expressed in force per unit area, such as megapascals (pounds-force per square inch).
3.1.1.1 Discussion—
The stress-strain relations of many plastics do not conform to Hooke’s law throughout the elastic range, but rather deviate
therefrom even at strains well below the elastic limit. For such materials, the slope of the tangent to the stress-strain curve at a low
strain is usually taken as the modulus of elasticity (or elastic modulus). Since the existence of a true proportional limit in
polyethylene is questionable, and with the impracticality of measuring it reliably, the use of secant modulus for comparative
evaluations is preferred.
3.1.2 secant modulus, n—the ratio of stress (nominal) to corresponding strain at any specified point on the stress-strain curve.
3.1.2.1 Discussion—
The measurement units for secant modulus may change, depending on the standard used. For the purposes of this practice, the
−2
measurement units shall be force per unit area (FL ), such as megapascals (pounds-force per square inch).
This practice is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.
Current edition approved June 1, 2011July 1, 2018. Published July 2011July 2018. Originally approved in 1992. Last previous edition approved in 20062011 as
D5323–92(2006).D5323 – 92 (2011). DOI: 10.1520/D5323-92R11.10.1520/D5323-92R18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5323 − 92 (2018)
4. Significance and Use
4.1 Where to draw the tangent to determine the modulus of elasticity is often unclear when performing tensile tests with
polyethylene geomembranes. This problem results in a wide variation in test results and thereforeand, therefore, makes this
property unreliable for comparisons.
4.2 A secant modulus based on 2 % strain can be useful when making comparisons between materials, in quality control, and
in comparing the same sample after being subjected to a nonstandard environment.
4.3 Secant modulus is an approximation of modulus of elasticity and generally results in a lower value than that for the modulus
of elasticity.
4.4 Although the technique for measuring 2 % secant modulus is described here, other percent secant moduli can be measured
by this practice.
5. Procedure
5.1 Follow the test procedure described in Test Method D638.
5.1.1 A cross-headcrosshead speed of 50 mm/min (2 ipm) is recommended for determining secant modulus, regardless of the
type of geomembrane being evaluate
...
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