ASTM D6992-16(2023)

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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.9 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.

General Information

• Status: Published
• Publication Date: 31-Aug-2023
• ICS: 59.080.70 - Geotextiles
• Technical Committee: D35 - Geosynthetics
• Drafting Committee: D35.02 - Endurance Properties

Standards Content (Sample)

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.
Designation: D6992 − 16 (Reapproved 2023)
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, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This test method covers accelerated testing for tensile
1.9 This international standard was developed in accor-
creep, and tensile creep-rupture properties using the Stepped
dance with internationally recognized principles on standard-
Isothermal Method (SIM).
ization established in the Decision on Principles for the
1.2 The test method is focused on geosynthetic reinforce-
Development of International Standards, Guides and Recom-
ment materials such as yarns, ribs of geogrids, or narrow
mendations issued by the World Trade Organization Technical
geotextile specimens.
Barriers to Trade (TBT) Committee.
1.3 The SIM tests are laterally unconfined tests based on
2. Referenced Documents
time-temperature superposition procedures.
2
2.1 ASTM Standards:
1.4 Tensile tests are to be completed before SIM tests and
D2990 Test Methods for Tensile, Compressive, and Flexural
the results are used to determine the stress levels for subse-
Creep and Creep-Rupture of Plastics
quent SIM tests defined in terms of the percentage of Ultimate
D4439 Terminology for Geosynthetics
Tensile Strength (T ). Additionally, the tensile test can be
ULT
D4595 Test Method for Tensile Properties of Geotextiles by
designed to provide estimates of the initial elastic strain
the Wide-Width Method
distributions appropriate for the SIM results.
D5262 Test Method for Determining the Unconfined Ten-
1.5 Ramp and Hold (R+H) tests may be completed in
sion Creep and Creep Rupture Behavior of Planar Geo-
conjunction with SIM tests. They are designed to provide
synthetics Used for Reinforcement Purposes
additional estimates of the initial elastic and initial rapid creep
3. Terminology
strain levels appropriate for the SIM results.
3.1 For definitions related to geosynthetics, see Terminol-
1.6 This method can be used to establish the sustained load
ogy D4439.
creep and creep-rupture characteristics of a geosynthetic.
Results of this method are to be used to augment results of Test
3.2 For definitions related to creep, see Test Methods D2990
Method D5262 and may not be used as the sole basis for
and D5262.
determination of long-term creep and creep-rupture behavior of
3.3 Definitions of Terms Specific to This Standard:
geosynthetic material.
3.3.1 creep modulus—in SIM analysis, the load divided by
1.7 The values stated in SI units are to be regarded as
the percent strain at any given point in time.
standard. No other units of measurement are included in this
3.3.2 dwell time—time during which conditions (particular
standard.
load) are held constant between temperature steps.
1.8 This standard does not purport to address all of the
3.3.3 mean test temperature—the arithmetic average of all
safety concerns, if any, associated with its use. It is the
temperature readings of the atmosphere surrounding the test
responsibility of the user of this standard to establish appro-
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.
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 Sept. 1, 2023. Published September 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2003. Last previous edition approved in 2016 as D6992 – 16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D6992-16R23. the ASTM website.
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D6992 − 16 (2023)
3.3.4 offset modulus method or pointing—data analysis 5.2 The statements set forth in 1.6 are very important in the
method used to norma
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