ASTM D7361-07(2023)
(Test Method)Standard Test Method for Accelerated Compressive Creep of Geosynthetic Materials Based on Time-Temperature Superposition Using the Stepped Isothermal Method
Standard Test Method for Accelerated Compressive Creep of Geosynthetic Materials Based on Time-Temperature Superposition Using the Stepped Isothermal Method
SIGNIFICANCE AND USE
5.1 Use of the SIM decreases the time required for creep to occur and the obtaining of the associated data.
5.2 The statements set forth in 1.5 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 drainage applications.
Note 1: Currently, SIM testing has focused mainly on geonets made from high-density polyethylene. Additional testing on other materials is ongoing.
5.4 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 compressive creep properties using the stepped isothermal method (SIM).
1.2 The test method is focused on geosynthetic drainage materials such as HDPE geonet specimens.
1.3 The SIM tests are laterally unconfined tests based on time-temperature superposition procedures.
1.4 Ramp and hold (R+H) tests may be completed in conjunction with SIM tests. They are designed to provide additional estimates of the initial rapid compressive creep strain levels appropriate for the SIM results.
1.5 This method can be used to establish the sustained load compressive creep characteristics of a geosynthetic that demonstrates a relationship between time-dependent behavior and temperature. Results of this method are to be used to augment results of compressive creep tests performed at 20 ± 1 °C and may not be used as the sole basis for determination of long-term compressive creep behavior of geosynthetic material.
1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.7 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.
1.8 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
Relations
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: D7361 − 07 (Reapproved 2023)
Standard Test Method for
Accelerated Compressive Creep of Geosynthetic Materials
Based on Time-Temperature Superposition Using the
Stepped Isothermal Method
This standard is issued under the fixed designation D7361; 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 mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method covers accelerated testing for compres-
sive creep properties using the stepped isothermal method
2. Referenced Documents
(SIM).
2.1 ASTM Standards:
1.2 The test method is focused on geosynthetic drainage
D1621 Test Method for Compressive Properties of Rigid
materials such as HDPE geonet specimens.
Cellular Plastics
1.3 The SIM tests are laterally unconfined tests based on D2990 Test Methods for Tensile, Compressive, and Flexural
time-temperature superposition procedures. Creep and Creep-Rupture of Plastics
D4439 Terminology for Geosynthetics
1.4 Ramp and hold (R+H) tests may be completed in
D5262 Test Method for Determining the Unconfined Ten-
conjunction with SIM tests. They are designed to provide
sion Creep and Creep Rupture Behavior of Planar Geo-
additional estimates of the initial rapid compressive creep
synthetics Used for Reinforcement Purposes
strain levels appropriate for the SIM results.
D6364 Test Method for Determining Short-Term Compres-
1.5 This method can be used to establish the sustained load
sion Behavior of Geosynthetics
compressive creep characteristics of a geosynthetic that dem-
onstrates a relationship between time-dependent behavior and 3. Terminology
temperature. Results of this method are to be used to augment
3.1 Definitions:
results of compressive creep tests performed at 20 6 1 °C and
3.1.1 For definitions related to geosynthetics, see Terminol-
may not be used as the sole basis for determination of
ogy D4439.
long-term compressive creep behavior of geosynthetic mate-
3.1.2 For definitions related to creep, see Test Methods
rial.
D2990 and D5262 and Terminology D4439.
1.6 The values stated in SI units are to be regarded as the 3.2 Definitions of Terms Specific to This Standard:
standard. The values given in parentheses are for information 3.2.1 compressive creep—time-dependent deformation that
only. occurs when a specimen is subjected to a constant compressive
load.
1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.2.2 compressive creep modulus—in SIM analysis, the load
responsibility of the user of this standard to establish appro- divided by the percent compressive strain at any given point in
priate safety, health, and environmental practices and deter- time.
mine the applicability of regulatory limitations prior to use.
3.2.3 dwell time—time during which conditions (particular
1.8 This international standard was developed in accor-
load) are held constant between temperature steps.
dance with internationally recognized principles on standard-
3.2.4 mean test temperature—the arithmetic average of all
ization established in the Decision on Principles for the
temperature readings of the atmosphere surrounding the test
Development of International Standards, Guides and Recom-
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.
This test method is under the jurisdiction of ASTM Committee D35 on
Geosynthetics and is the direct responsibility of Subcommittee D35.02 on Endur-
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 service@astm.org. For Annual Book of ASTM
approved in 2007. Last previous edition approved in 2018 as D7361 – 07 (2018). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D7361-07R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7361 − 07 (2023)
3.2.5 offset modulus method or pointing—data analysis 6.2 Testing Machine—A universal testing machine or a
method used to normalize any prestrain in the samples by dead-weight loading system with the following capabilities and
shifting the origin of a stress-versus-strain curve to an axis accessories shall be used for testing:
origin of coordinates, that is, to coordinates (0,0). 6.2.1 Load measurement and control,
6.2.2 Strain measurement,
3.2.6 ramp and hold (R+H) test—a creep test of very short
6.2.3 Time measurement,
duration, for example, 100 to 1000 s.
6.2.4 Environmental temperature chamber to facilitate con-
3.2.7 shift factor—the displacement along the log time axis
trol of test conditions,
by which a section of the creep or creep modulus curve is
6.2.4.1 Temperature measurement and control facilities,
moved to create the master curve at the reference temperature.
6.2.5 Other environmental measurement and control, and
Shift factors are denoted by the symbol ~ when the displace-
6.2.6 Computer data acquisition and control.
ments are generally to shorter times (attenuation) or the symbol
a when the displacements are generally to longer times
T
7. Sampling
(acceleration).
7.1 The specimens used for R+H and SIM tests should all be
3.2.8 stepped isothermal method (SIM)—a method of expo-
taken from the same sample.
sure that uses temperature steps and dwell times to accelerate
7.2 Remove one (1) test specimen from the sample for each
creep response of a material being tested under load.
SIM test.
3.2.9 time-temperature superposition—the practice of shift-
7.3 Remove one (1) test specimen from the sample for each
ing viscoelastic response curves obtained at different tempera-
R+H test.
tures along a horizontal log time axis so as to achieve a master
curve covering an extended range of time.
8. Test Specimens
3.2.10 viscoelastic response—refers to polymeric creep,
8.1 Specimens should be at least 120 by 120 mm (4.7 by
strain, stress relaxation, or a combination thereof.
4.7 in.).
4. Summary of Test Method
8.2 Number of Tests:
4.1 SIM—A procedure whereby specified temperature steps
8.2.1 A single specimen is usually sufficient to define a
and dwell times are used to accelerate viscoelastic creep
master creep or relaxation curve using the SIM. However, if
characteristics during which strain and load are monitored as a
only a single SIM test is to be performed, the location of the
function of time.
onset of creep strain or modulus curve should be confirmed
4.1.1 Compressive Creep—Constant compressive load in
using at least two R+H tests.
conjunction with specified temperature steps and dwell times
are used to accelerate compressive creep strain response.
9. Conditioning
4.2 R+H—Test specimens are ramp loaded at a predeter-
9.1 Compression testing via Test Method D6364 and SIM
mined loading rate to a predetermined load and held under
testing shall be conducted using 20 6 1 °C as the reference or
constant load (short-term creep test).
temperature standard. If the laboratory is not within this range,
perform tests in a suitable environmental chamber capable of
5. Significance and Use
controlled cooling and heating. The environmental chamber
5.1 Use of the SIM decreases the time required for creep to
should have a programmable or set-point controller so as to
occur and the obtaining of the associated data.
maintain temperature to 20 6 1 °C. When agreed to, a
5.2 The statements set forth in 1.5 are very important in the
reference temperature other than 20 °C can be utilized. Also,
context of significance and use, as well as scope of the
when agreed to, the results of testing under this standard can be
standard.
shifted from one reference temperature to another.
5.3 Creep test data are used to calculate the creep modulus
9.2 Allow the specimen adequate time to come to tempera-
of materials as a function of time. These data are then used to
ture equilibrium in the laboratory or environmental chamber.
predict the long-term creep deformation expected of geosyn-
Generally, this can be accomplished within a few hours (see
thetics used in drainage applications.
Note 2).
NOTE 1—Currently, SIM testing has focused mainly on geonets made
9.3 Record the relative humidity in the laboratory or envi-
from high-density polyethylene. Additional testing on other materials is
ronmental chamber for all tests.
ongoing.
5.4 R+H testing is done to establish the range of creep
10. Selection of Test Conditions
strains experienced in the brief period of very rapid response
10.1 The standard environment for testing is dry, since the
following the peak of the load ramp.
effect of elevated temperature is to reduce the humidity of
ambient air without special controls.
6. Apparatus
6.1 Loading Platens—Loading platens for SIM and R+H 10.2 The standard reference temperature is 20 °C unless
tests should conform to Test Method D6364, Standard Test otherwise agreed to. The individual reference temperature for
Method for Determining the Short-Term Compression Behav- each SIM test is the average achieved temperature of the first
ior of Geosynthetics. dwell time.
...
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