Standard Test Method for Measuring Stiffness and Apparent Modulus of Soil and Soil-Aggregate In-Place by Electro-Mechanical Method

SIGNIFICANCE AND USE
4.1 The apparatus and procedure described provides a means for measurement of the stiffness of a layer of soil or soil-aggregate mixture from which a Young's modulus may be determined for an assumed Poisson's ratio. Low strain cyclic loading is applied by the apparatus about a static load that is consistent with highway applications (1).  
4.2 This method is useful as a non-destructive method for monitoring or controlling compaction so as to avoid under-compaction, over-compaction or wasted effort. Through an understanding of how stiffness relates to density for a particular material, moisture content and compaction procedure, the stiffness achieved can be related to % compaction in connection with density based compaction control or specifications, for example, to meet the requirements of Method D698 using standard effort or Method D1557 using modified effort.  
4.2.1 This method applies to silty and clayey materials containing greater than 20 % fines. In such cases, the relationship between stiffness and dry density or dry unit weight is sensitive to the water content. Water contents should be determined by use of: Test Method D2216, D4643, or D4959. If the determination cannot be made immediately at the time of the stiffness measurements, then soil samples shall be preserved and transported in accordance with Practice D4220, Section 8, Groups B, C, or D soils.  
4.2.2 This method is useful in the construction of road bases or earthworks, including the installation of buried pipe (2).  
4.2.3 The rapid, non-penetrating nature of this method is suited to production testing, for example, it provides a means of testing that does not necessarily interfere with or delay construction.  
4.3 This method is suitable for mitigating the risk of pavement failure. By assuring the relative uniformity of highway subbase, subgrade and base stiffnesses, stresses on the pavement is more uniformly distributed. In this way the life of a pavement is extended and repairs minimiz...
SCOPE
1.1 This test method covers the measurement by electro-mechanical means of the in-place stiffness of soil or soil-aggregate mixtures so as to determine a Young's modulus based on certain assumptions. The apparatus and procedure provide a fairly rapid means of testing so as to minimize interference and delay of construction. The test procedure is intended for evaluating the stiffness or modulus of materials used in earthworks and roadworks. Rapid in-place stiffness testing supports U.S. federal and state efforts to specify the in-place performance of construction materials based on modulus. Results obtained from this method are applicable to the evaluation of granular cohesionless materials. They are also applicable to the evaluation of silty and clayey materials with more than 20 % fines that are not subject to a change in moisture content. If the silty and clayey material experiences a change in moisture content, then moisture content shall be taken into account if the results of this method are to be applicable. The stiffness measured with this method is influenced by boundary conditions, specifically the support offered by underlying layers as well as the thickness and modulus of the layer being tested. Since this method approximates the layer(s) being evaluated as a half-space, then the modulus measured is also approximate.  
1.2 The stiffness, in force per unit displacement, is determined by imparting a small measured force to the surface of the ground, measuring the resulting surface velocity and calculating the stiffness. This is done over a frequency range and the results are averaged.  
1.3 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only and are not considered standard.  
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 sta...

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Publication Date
14-Feb-2018
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ASTM D6758-18e1 - Standard Test Method for Measuring Stiffness and Apparent Modulus of Soil and Soil-Aggregate In-Place by Electro-Mechanical Method
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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.
´1
Designation: D6758 − 18
Standard Test Method for
Measuring Stiffness and Apparent Modulus of Soil and Soil-
1
Aggregate In-Place by Electro-Mechanical Method
This standard is issued under the fixed designation D6758; 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—Editorially corrected units of measurement statement in June 2021.
1. Scope 1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the measurement by electro-
responsibility of the user of this standard to establish appro-
mechanical means of the in-place stiffness of soil or soil-
priate safety, health, and environmental practices and deter-
aggregate mixtures so as to determine a Young’s modulus
mine the applicability of regulatory limitations prior to use.
based on certain assumptions. The apparatus and procedure
provide a fairly rapid means of testing so as to minimize NOTE 1—Notwithstanding the statements on precision and bias con-
tained in this test method; the precision of this test method is dependent
interference and delay of construction. The test procedure is
onthecompetenceofthepersonnelperformingit,andthesuitabilityofthe
intended for evaluating the stiffness or modulus of materials
equipment and facilities used. Agencies that meet the criteria of Practice
used in earthworks and roadworks. Rapid in-place stiffness
D3740 are generally considered capable of competent and objective
testing supports U.S. federal and state efforts to specify the
testing. Users of this test method are cautioned that compliance with
in-placeperformanceofconstructionmaterialsbasedonmodu- Practice D3740 does not in itself assure reliable testing. Reliable testing
depends on many factors; Practice D3740 provides a means of evaluating
lus. Results obtained from this method are applicable to the
some of those factors.
evaluation of granular cohesionless materials. They are also
1.5 This international standard was developed in accor-
applicable to the evaluation of silty and clayey materials with
dance with internationally recognized principles on standard-
more than 20 % fines that are not subject to a change in
ization established in the Decision on Principles for the
moisture content. If the silty and clayey material experiences a
Development of International Standards, Guides and Recom-
change in moisture content, then moisture content shall be
mendations issued by the World Trade Organization Technical
taken into account if the results of this method are to be
Barriers to Trade (TBT) Committee.
applicable. The stiffness measured with this method is influ-
enced by boundary conditions, specifically the support offered
2. Referenced Documents
by underlying layers as well as the thickness and modulus of
2
the layer being tested. Since this method approximates the
2.1 ASTM Standards:
layer(s) being evaluated as a half-space, then the modulus
D653 Terminology Relating to Soil, Rock, and Contained
measured is also approximate.
Fluids
D698 Test Methods for Laboratory Compaction Character-
1.2 The stiffness, in force per unit displacement, is deter-
3
istics of Soil Using Standard Effort (12,400 ft-lbf/ft (600
mined by imparting a small measured force to the surface of
3
kN-m/m ))
the ground, measuring the resulting surface velocity and
D1557 Test Methods for Laboratory Compaction Character-
calculating the stiffness. This is done over a frequency range
3
istics of Soil Using Modified Effort (56,000 ft-lbf/ft
and the results are averaged.
3
(2,700 kN-m/m ))
1.3 Units—The values stated in SI units are to be regarded
D2216 Test Methods for Laboratory Determination of Water
as standard. The values given in parentheses are provided for
(Moisture) Content of Soil and Rock by Mass
information only and are not considered standard.
D3740 Practice for Minimum Requirements for Agencies
Engaged in Testing and/or Inspection of Soil and Rock as
Used in Engineering Design and Construction
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.08 on Special and
Construction Control Tests.
2
Current edition approved Feb. 15, 2018. Published February 2018. Originally For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approved in 2002. Last previous edition approved in 2008 as D6758 – 08, which contact ASTM Customer Service at service@as
...

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