ASTM D1883-16
(Test Method)Standard Test Method for California Bearing Ratio (CBR) of Laboratory-Compacted Soils
Standard Test Method for California Bearing Ratio (CBR) of Laboratory-Compacted Soils
SIGNIFICANCE AND USE
5.1 This test method is used to evaluate the potential strength of subgrade, subbase, and base course materials, including recycled materials for use in the design of road and airfield pavements. The CBR value obtained in this test forms an integral part of several flexible pavement design methods.
5.2 For applications where the effect of compaction water content on CBR is small, such as cohesionless, coarse-grained materials, or where an allowance is made for the effect of differing compaction water contents in the design procedure, the CBR may be determined at the optimum water content of a specified compaction effort. The specified dry unit weight is normally the minimum percent compaction allowed by the using client’s field compaction specification.
5.3 For applications where the effect of compaction water content on CBR is unknown or where it is desired to account for its effect, the CBR is determined for a range of water contents, usually the range of water content permitted for field compaction by using the client’s protocol or specification for field compaction.
5.4 The criteria for test specimen preparation of self-cementing (and other) materials which gain strength with time must be based on a geotechnical engineering evaluation. As directed by the client, self-cementing materials shall be properly cured until bearing ratios representing long term service conditions can be measured.
Note 1: The quality of the results produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
SCOPE
1.1 This test method covers the determination of the California Bearing Ratio (CBR) of pavement subgrade, subbase, and base course materials from laboratory compacted specimens. The test method is primarily intended for, but not limited to, evaluating the strength of materials having maximum particle size less than 3/4 in. (19 mm).
1.2 When materials having a maximum particle size greater than 3/4 in. (19 mm) are to be tested, this test method provides for modifying the gradation of the material so that the material used for testing all passes the 3/4-in. (19-mm) sieve while the total gravel fraction (material passing the 3-in. (75-mm) sieve and retained on the No. 4 (4.75-mm) sieve) remains the same. While traditionally this method of specimen preparation has been used to avoid the error inherent in testing materials containing large particles in the CBR test apparatus, the modified material may have significantly different strength properties than the original material. However, a large experience database has been developed using this test method for materials for which the gradation has been modified, and satisfactory design methods are in use based on the results of tests using this procedure.
1.3 Past practice has shown that CBR results for those materials having substantial percentages of particles retained on the No. 4 (4.75 mm) sieve are more variable than for finer materials. Consequently, more trials may be required for these materials to establish a reliable CBR.
1.4 This test method provides for the determination of the CBR of a material at optimum water content or a range of water content from a specified compaction test and a specified dry unit weight. The dry unit weight is usually given as a percentage of maximum dry unit weight determined by Test Methods D698 or D1557.
1.5 The client requesting the test may specify the water content or range of water contents and the dry unit weight for which the CBR is desired.
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Designation: D1883 − 16
Standard Test Method for
California Bearing Ratio (CBR) of Laboratory-Compacted
1
Soils
This standard is issued under the fixed designation D1883; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* 1.5 The client requesting the test may specify the water
content or range of water contents and the dry unit weight for
1.1 This test method covers the determination of the Cali-
which the CBR is desired.
fornia Bearing Ratio (CBR) of pavement subgrade, subbase,
and base course materials from laboratory compacted speci-
1.6 Unless specified otherwise by the requesting client, or
mens.Thetestmethodisprimarilyintendedfor,butnotlimited
unlessithasbeenshowntohavenoeffectontestresultsforthe
to, evaluating the strength of materials having maximum
material being tested, all specimens shall be soaked prior to
3
particle size less than ⁄4 in. (19 mm).
penetration.
1.2 When materials having a maximum particle size greater
1.7 For the determination of CBR of field in-place
3
than ⁄4 in. (19 mm) are to be tested, this test method provides
materials, see Test Method D4429.
for modifying the gradation of the material so that the material
1.8 Units—The values stated in inch-pound units are to be
3
used for testing all passes the ⁄4-in. (19-mm) sieve while the
regarded as standard. The SI units given in parentheses are
total gravel fraction (material passing the 3-in. (75-mm) sieve
mathematical conversions, which are provided for information
and retained on the No. 4 (4.75-mm) sieve) remains the same.
purposes only and are not considered standard. Reporting of
While traditionally this method of specimen preparation has
test results in units other than inch-pound units shall not be
been used to avoid the error inherent in testing materials
regarded as nonconformance with this test method.
containing large particles in the CBR test apparatus, the
1.8.1 The gravitational system of inch-pound units is used
modified material may have significantly different strength
when dealing with inch-pound units. In this system, the pound
properties than the original material. However, a large experi-
(lbf)representsaunitofforce(weight),whiletheunitformass
ence database has been developed using this test method for
is slugs. The slug unit is not given, unless dynamic (F = ma)
materials for which the gradation has been modified, and
calculations are involved.
satisfactory design methods are in use based on the results of
1.8.2 The slug unit of mass is almost never used in
tests using this procedure.
commercial practice; that is, density, balances, etc. Therefore,
1.3 Past practice has shown that CBR results for those
the standard unit for mass in this standard is either kilogram
materials having substantial percentages of particles retained
(kg) or gram (g), or both.Also, the equivalent inch-pound unit
on the No. 4 (4.75 mm) sieve are more variable than for finer
(slug) is not given/presented in parentheses.
materials. Consequently, more trials may be required for these
1.8.3 It is common practice in the engineering/construction
materials to establish a reliable CBR.
profession, in the United States, to concurrently use pounds to
1.4 This test method provides for the determination of the
represent both a unit of mass (lbm) and of force (lbf). This
CBR of a material at optimum water content or a range of
implicitly combines two separate systems of units; that is, the
water content from a specified compaction test and a specified
absolutesystemandthegravitationalsystem.Itisscientifically
dry unit weight. The dry unit weight is usually given as a
undesirable to combine the use of two separate sets of
percentage of maximum dry unit weight determined by Test
inchpound units within a single standard. As stated, this
Methods D698 or D1557.
standard includes the gravitational system of inch-pound units
and does not use/present the slug unit for mass. However, the
use of balances or scales recording pounds of mass (lbm) or
3
1 recording density in lbm/ft shall not be regarded as noncon-
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
formance with this standard.
Compressibility of Soils.
1.8.4 The terms density and unit weight are often used
Current edition approved March 1, 2016. Published March 2016. Originally
interchangeably. Density is mass per unit volume whereas unit
approved in 1961. Last previous edition approved in 2014 as D1883–14. DOI:
10.
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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: D1883 − 14 D1883 − 16
Standard Test Method for
California Bearing Ratio (CBR) of Laboratory-Compacted
1
Soils
This standard is issued under the fixed designation D1883; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This test method covers the determination of the California Bearing Ratio (CBR) of pavement subgrade, subbase, and base
course materials from laboratory compacted specimens. The test method is primarily intended for, but not limited to, evaluating
3
the strength of materials having maximum particle size less than ⁄4 in. (19 mm).
3
1.2 When materials having a maximum particle size greater than ⁄4 in. (19 mm) are to be tested, this test method provides for
3
modifying the gradation of the material so that the material used for teststesting all passes the ⁄4-in. (19-mm) sieve while the total
gravel (3 in. (75 mm) to plus No. 4 (4.75 mm)) fraction fraction (material passing the 3-in. (75-mm) sieve and retained on the No.
4 (4.75-mm) sieve) remains the same. While traditionally this method of specimen preparation has been used to avoid the error
inherent in testing materials containing large particles in the CBR test apparatus, the modified material may have significantly
different strength properties than the original material. However, a large experience database has been developed using this test
method for materials for which the gradation has been modified, and satisfactory design methods are in use based on the results
of tests using this procedure.
1.3 Past practice has shown that CBR results for those materials having substantial percentages of particles retained on the No.
4 (4.75 mm) sieve are more variable than for finer materials. Consequently, more trials may be required for these materials to
establish a reliable CBR.
1.4 This test method provides for the determination of the CBR of a material at optimum water content or a range of water
content from a specified compaction test and a specified dry unit weight. The dry unit weight is usually given as a percentage of
maximum dry unit weight determined by Test Methods D698 or D1557.
1.5 The client requesting the test may specify the water content or range of water contents and the dry unit weight for which
the CBR is desired.
1.6 Unless specified otherwise by the requesting client, or unless it has been shown to have no effect on test results for the
material being tested, all specimens shall be soaked prior to penetration.
1.7 For the determination of CBR of field in-place materials, see Test Method D4429.
1.8 Units—The values stated in inch-pound units are to be regarded as standard. The SI units given in parentheses are
mathematical conversions, which are provided for information purposes only and are not considered standard. Reporting of test
results in units other than inch-pound units shall not be regarded as nonconformance with this test method.
1.8.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf)
represents a unit of force (weight), while the unit for mass is slugs. The slug unit is not given, unless dynamic (F = ma) calculations
are involved.
1.8.2 The slug unit of mass is almost never used in commercial practice; that is, density, balances, etc. Therefore, the standard
unit for mass in this standard is either kilogram (kg) or gram (g), or both. Also, the equivalent inch-pound unit (slug) is not
given/presented in parentheses.
1.8.3 It is common practice in the engineering/construction profession, in the United States, to concurrently use pounds to
represent both a unit of mass (lbm) and of force (lbf). This implicitly combines two separate systems of units; that is, the absolute
system and the gravitational system. It is scientifically undesirable to combine the use of two separate sets of inchpound units
1
This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
Compressibility of Soils.
Current edition approved Dec. 1, 2014March 1, 2016. Published January 2015March 2016. Originally approved in 1961. Last previous edition approved in 20072014 as
ϵ2
D1883 – 07D1883 – 14. . DO
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