ASTM D6992-16

Standard Test Method for Accelerated Tensile Creep and Creep-Rupture of Geosynthetic Materials Based on Time-Temperature Superposition Using the Stepped Isothermal Method

SIGNIFICANCE AND USE
5.1 Use of the Stepped Isothermal Method decreases the time required for creep to occur and the obtaining of the associated data.  
5.2 The statements set forth in 1.6 are very important in the context of significance and use, as well as scope of the standard.  
5.3 Creep test data are used to calculate the creep modulus of materials as a function of time. These data are then used to predict the long-term creep deformation expected of geosynthetics used in reinforcement applications.
Note 1: Currently, SIM testing has focused mainly on woven and knitted geogrids and woven geotextiles made from polyester, aramid, polyaramid, poly-vinyl alcohol (PVA) and polypropylene yarns and narrow strips. Additional correlation studies on other materials are needed.  
5.4 Creep rupture test data are used to develop a regression line relating creep stress to rupture time. These results predict the long term rupture strength expected for geosynthetics in reinforcement applications.  
5.5 Tensile testing is used to establish the ultimate tensile strength (TULT) of a material and to determine elastic stress, strain and variations thereof for SIM tests.  
5.6 Ramp and Hold (R+H) testing is done to establish the range of creep strains experienced in the brief period of very rapid response following the peak of the load ramp.
SCOPE
1.1 This test method covers accelerated testing for tensile creep, and tensile creep-rupture properties using the Stepped Isothermal Method (SIM).  
1.2 The test method is focused on geosynthetic reinforcement materials such as yarns, ribs of geogrids, or narrow geotextile specimens.  
1.3 The SIM tests are laterally unconfined tests based on time-temperature superposition procedures.  
1.4 Tensile tests are to be completed before SIM tests and the results are used to determine the stress levels for subsequent SIM tests defined in terms of the percentage of Ultimate Tensile Strength (TULT). Additionally, the tensile test can be designed to provide estimates of the initial elastic strain distributions appropriate for the SIM results.  
1.5 Ramp and Hold (R+H) tests may be completed in conjunction with SIM tests. They are designed to provide additional estimates of the initial elastic and initial rapid creep strain levels appropriate for the SIM results.  
1.6 This method can be used to establish the sustained load creep and creep-rupture characteristics of a geosynthetic. Results of this method are to be used to augment results of Test Method D5262 and may not be used as the sole basis for determination of long term creep and creep-rupture behavior of geosynthetic material.  
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.8 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: 14-Feb-2016
• ICS: 59.080.70 - Geotextiles
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.02 - Endurance Properties

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
Designation: D6992 − 16
Standard Test Method for
Accelerated Tensile Creep and Creep-Rupture of
Geosynthetic Materials Based on Time-Temperature
1
Superposition Using the Stepped Isothermal Method
This standard is issued under the fixed designation D6992; 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 priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This test method covers accelerated testing for tensile
creep, and tensile creep-rupture properties using the Stepped
2. Referenced Documents
Isothermal Method (SIM).
2
2.1 ASTM Standards:
1.2 The test method is focused on geosynthetic reinforce-
D2990 Test Methods for Tensile, Compressive, and Flexural
ment materials such as yarns, ribs of geogrids, or narrow
Creep and Creep-Rupture of Plastics
geotextile specimens.
D4439 Terminology for Geosynthetics
1.3 The SIM tests are laterally unconfined tests based on D4595 Test Method for Tensile Properties of Geotextiles by
time-temperature superposition procedures. the Wide-Width Strip Method
D5262 Test Method for Evaluating the Unconfined Tension
1.4 Tensile tests are to be completed before SIM tests and
Creep and Creep Rupture Behavior of Geosynthetics
the results are used to determine the stress levels for subse-
quent SIM tests defined in terms of the percentage of Ultimate
3. Terminology
Tensile Strength (T ). Additionally, the tensile test can be
ULT
3.1 For definitions related to geosynthetics see Terminology
designed to provide estimates of the initial elastic strain
D4439.
distributions appropriate for the SIM results.
3.2 For definitions related to creep see Test Methods D2990
1.5 Ramp and Hold (R+H) tests may be completed in
and D5262.
conjunction with SIM tests. They are designed to provide
additional estimates of the initial elastic and initial rapid creep
3.3 Definitions of Terms Specific to This Standard:
strain levels appropriate for the SIM results.
3.3.1 creep modulus—in SIM analysis, the load divided by
the percent strain at any given point in time.
1.6 This method can be used to establish the sustained load
3.3.2 dwell time—time during which conditions (particular
creep and creep-rupture characteristics of a geosynthetic.
load) are held constant between temperature steps.
Results of this method are to be used to augment results of Test
Method D5262 and may not be used as the sole basis for
3.3.3 mean test temperature—the arithmetic average of all
determination of long term creep and creep-rupture behavior of
temperature readings of the atmosphere surrounding the test
geosynthetic material.
specimen for a particular temperature step, starting at a time
not later than established temperature ramp time, and finishing
1.7 The values stated in SI units are to be regarded as
at a time just prior to the subsequent temperature reset.
standard. No other units of measurement are included in this
standard. 3.3.4 offset modulus method or pointing—data analysis
method used to normalize any prestrain in the samples by
1.8 This standard does not purport to address all of the
shifting the origin of a stress versus strain curve to an axis
safety concerns, if any, associated with its use. It is the
origin of coordinates; that is, to coordinates (0,0).
responsibility of the user of this standard to establish appro-
3.3.5 ramp and hold (R+H) test—a creep test of very short
duration; for example, 100 to 1000 s.
1
This test method is under the jurisdiction of ASTM Committee D35 on
Geosynthetics and is the direct responsibility of Subcommittee D35.02 on Endur-
2
ance Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 15, 2016. Published February 2016. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2003. Last previous edition approved in 2015 as D6992 – 03(2015). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6992-16. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D6992 − 16
3.3.6 shift factor—the displacement along the log time axis predict the long-term creep deformation expected of geosyn-
by which a section of the creep or creep modulus curve is thetics used in reinforcement applications.
NOTE 1—Currently, SIM testing has focused mainly on woven and
moved to create the master curve at the reference temperature.
knitted geogrids and wo
...

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: D6992 − 03 (Reapproved 2015) D6992 − 16
Standard Test Method for
Accelerated Tensile Creep and Creep-Rupture of
Geosynthetic Materials Based on Time-Temperature
1
Superposition Using the Stepped Isothermal Method
This standard is issued under the fixed designation D6992; 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 test method covers accelerated testing for tensile creep, and tensile creep-rupture properties using the Stepped
Isothermal Method (SIM).
1.2 The test method is focused on geosynthetic reinforcement materials such as yarns, ribs of geogrids, or narrow geotextile
specimens.
1.3 The SIM tests are laterally unconfined tests based on time-temperature superposition procedures.
1.4 Tensile tests are to be completed before SIM tests and the results are used to determine the stress levels for subsequent SIM
tests defined in terms of the percentage of Ultimate Tensile Strength (T ). Additionally, the tensile test can be designed to provide
ULT
estimates of the initial elastic strain distributions appropriate for the SIM results.
1.5 Ramp and Hold (R+H) tests may be completed in conjunction with SIM tests. They are designed to provide additional
estimates of the initial elastic and initial rapid creep strain levels appropriate for the SIM results.
1.6 This method can be used to establish the sustained load creep and creep-rupture characteristics of a geosynthetic. Results
of this method are to be used to augment results of Test Method D5262 and may not be used as the sole basis for determination
of long term creep and creep-rupture behavior of geosynthetic material.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 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:
D2990 Test Methods for Tensile, Compressive, and Flexural Creep and Creep-Rupture of Plastics
D4439 Terminology for Geosynthetics
D4595 Test Method for Tensile Properties of Geotextiles by the Wide-Width Strip Method
D5262 Test Method for Evaluating the Unconfined Tension Creep and Creep Rupture Behavior of Geosynthetics
3. Terminology
3.1 For definitions related to geosynthetics see Terminology D4439.
3.2 For definitions related to creep see Test Methods D2990 and D5262.
3.3 Definitions of Terms Specific to This Standard:
3.3.1 creep modulus—in SIM analysis, the load divided by the percent strain at any given point in time.
3.3.2 dwell time—time during which conditions (particular load) are held constant between temperature steps.
1
This test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is the direct responsibility of Subcommittee D35.02 on Endurance Properties.
Current edition approved May 1, 2015Feb. 15, 2016. Published June 2015February 2016. Originally approved in 2003. Last previous edition approved in 20092015 as
D6992 – 03(2009).03(2015). DOI: 10.1520/D6992-03R15.10.1520/D6992-16.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D6992 − 16
3.3.3 mean test temperature—the arithmetic average of all temperature readings of the atmosphere surrounding the test
specimen for a particular temperature step, starting at a time not later than established temperature ramp time, and finishing at a
time just prior to the subsequent temperature reset.
3.3.4 offset modulus method or pointing—data analysis method used to normalize any prestrain in the samples by shifting the
origin of a stress versus strain curve to an axis origin of coordinates; that is, to coordinates (0,0).
3.3.5 ramp and hold (R+H) test—a creep test of very short duration; for example, 100 to 1000 s.
3.3.6 shift factor—the displ
...