ASTM D3282-93(1997)e1
(Classification)Standard Classification of Soils and Soil-Aggregate Mixtures for Highway Construction Purposes
Standard Classification of Soils and Soil-Aggregate Mixtures for Highway Construction Purposes
SCOPE
1.1 This standard describes a procedure for classifying mineral and organomineral soils into seven groups based on laboratory determination of particle-size distribution, liquid limit, and plasticity index. It may be used when a precise engineering classification is required, especially for highway construction purposes. Evaluation of soils within each group is made by means of a group index , which is a value calculated from an empirical formula. Note 1-The group classification, including the group index, should be useful in determining the relative quality of the soil material for use in earthwork structures, particularly embankments, subgrades, subbases, and bases. However, for the detailed design of important structures, additional data concerning strength or performance characteristics of the soil under field conditions will usually be required.
1.2 This standard does not purport to address all of the safety problems, 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.
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e1
Designation: D 3282 – 93 (Reapproved 1997)
Standard Practice for
Classification of Soils and Soil-Aggregate Mixtures for
Highway Construction Purposes
This standard is issued under the fixed designation D 3282; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—The title was corrected and Section 1.3 was added editorially in January 1999.
1. Scope 2. Referenced Documents
1.1 This standard describes a procedure for classifying 2.1 ASTM Standards:
mineral and organomineral soils into seven groups based on D 420 Guide to Site Characterization for Engineering De-
laboratory determination of particle-size distribution, liquid sign and Construction Purposes
limit, and plasticity index. It may be used when a precise D 421 Practice for Dry Preparation of Soil Samples for
engineering classification is required, especially for highway Particle-Size Analysis and Determination of Soil Con-
construction purposes. Evaluation of soils within each group is stants
made by means of a group index, which is a value calculated D 422 Test Method for Particle-Size Analysis of Soils
from an empirical formula. D 653 Terminology Relating to Soil, Rock, and Contained
Fluids
NOTE 1—The group classification, including the group index, should be
D 1140 Test Method for Amount of Material in Soils Finer
useful in determining the relative quality of the soil material for use in
Than the No. 200 (75-μm) Sieve
earthwork structures, particularly embankments, subgrades, subbases, and
bases. However, for the detailed design of important structures, additional D 1452 Practice for Soil Investigation and Sampling by
data concerning strength or performance characteristics of the soil under
Auger Borings
field conditions will usually be required.
D 1586 Test Method for Penetration Test and Split-Barrel
Sampling of Soils
1.2 This standard does not purport to address all of the
D 1587 Practice for Thin-Walled Tube Getotechnical Sam-
safety concerns, if any, associated with its use. It is the
pling of Soils
responsibility of the user of this standard to establish appro-
D 2217 Practice for Wet Preparation of Soil Samples for
priate safety and health practices and determine the applica-
Particle-Size Analysis and Determination of Soil Con-
bility of regulatory limitations prior to use.
stants
1.3 This practice offers a set of instructions for performing
D 4318 Test Method for Liquid Limit, Plastic Limit, and
one or more specific operations. This document cannot replace
Plasticity Index of Soils
education or experience and should be used in conjunction
2.2 AASHTO Document:
with professional judgment. Not all aspects of this practice may
M 145 The Classification of Soils and Soil Aggregate Mix-
be applicable in all circumstances. This ASTM standard is not
tures for Highway Construction Purposes
intended to represent or replace the standard of care by which
the adequacy of a given professional service must be judged,
3. Terminology
nor should this document be applied without consideration of
3.1 Definitions of Terms Specific to This Standard:
a project’s many unique aspects. The word “Standard” in the
3.1.1 The following terms are frequently used in this stan-
title of this document means only that the document has been
dard. These terms differ slightly from those given in Terminol-
approved through the ASTM consensus process.
ogy D 653, but are used here to maintain consistency with
common highway usage.
This standard is under the jurisdiction of ASTM Committee D-18 on Soil and
Rock and is the direct responsibility of Subcommittee D18.07 on Identification and
Classification of Soils. Annual Book of ASTM Standards, Vol 04.08.
Current edition approved Sept. 15, 1993. Published November 1993. Originally
Available from American Asssociation of State Highway and Transportation
published as D 3282–73. Last previous edition D 3282 – 92. Officials, 444 N Capitol St., NW, Suite 225, Washington, DC 20001.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 3282
3.1.2 boulders—rock fragments, usually rounded by weath- 6.1.1 Guide D 420,
ering or abrasion, that will be retained on a 3-in. (75-mm) 6.1.2 Practice D 1452,
sieve. 6.1.3 Method D 1586,
3.1.3 coarse sand—particles of rock or soil that will pass a 6.1.4 Practice D 1587.
No. 10 (2-mm) sieve and be retained on a No. 40 (425-μm)
7. Test Sample
sieve.
7.1 Test samples shall represent that portion of the field
3.1.4 fine sand—particles of rock or soil that will pass a No.
sample finer than the 3-in. (75-mm) sieve and shall be obtained
40 (425-μm) sieve and be retained on a No. 200 (75-μm) sieve.
as follows:
3.1.5 gravel—particles of rock that will pass a 3-in. (75-
7.1.1 Air-dry the field sample,
mm) sieve and be retained on a No. 10 (2-mm) sieve.
7.1.2 Weigh the field sample,
3.1.6 silt-clay (combined silt and clay)—fine soil and rock
7.1.3 Separate the field sample into two fractions on a 3-in.
particles that will pass a No. 200 (75-μm) sieve.
(75-mm) sieve,
3.1.7 silty—fine-grained material that has a plasticity index
7.1.4 Weigh the fraction retained on the 3-in. (75-mm)
of 10 or less.
sieve. Compute the percentage of plus 3-in. material in the field
3.1.8 clayey—fine-grained material that has a plasticity
sample, and note this percentage as auxiliary information, and
index of 11 or more.
7.1.5 Thoroughly mix the fraction passing the 3-in. (75-
4. Significance and Use
mm) sieve and select the test samples.
4.1 The standard described classifies soils from any geo-
NOTE 2—If visual examination indicates that no boulder size material is
graphic location into groups (including group indexes) based
present, omit 7.1.3 and 7.1.4.
on the results of prescribed laboratory tests to determine the
7.2 Prepare the test sample in accordance with Practices
particle-size characteristics, liquid limit, and plasticity index.
D 421 or D 2217. Determine the percentage of the sample finer
4.2 The assigning of a group symbol and group index can be
than a No. 10 (2-mm) sieve.
used to aid in the evaluation of the significant properties of the
NOTE 3—It is recommended that the method for wet preparation be
soil for highway and airfield purposes.
used for soils containing organic matter or irreversible mineral colloids.
4.3 The various groupings of this classification system
correlate in a general way with the engineering behavior of
8. Testing Procedure
soils. Also, in a general way, the engineering behavior of a soil
8.1 Determine the percentage of the test sample finer than a
varies inversely with its group index. Therefore, this standard
No. 200 (75-μm) sieve in accordance with Test Methods
provides a useful first step in any field or laboratory investi-
D 1140 or D 422.
gation for geotechnical engineering purposes.
NOTE 4—For granular materials the percentage of the sample finer than
5. Apparatus
a No. 40 (425-μm) sieve must also be determined.
5.1 Apparatus for Preparation of Samples—See Practices
8.2 Determine the liquid limit and the plasticity index of a
D 421 or D 2217.
portion of the test sample passing a No. 40 (425-μm) sieve in
5.2 Apparatus for Particle-Size Analysis—See Test Meth-
accordance with Test Method D 4318.
ods D 1140 and D 422.
9. Classification Procedure
5.3 Apparatus for Liquid Limit and Plastic Limit Tests—See
9.1 Using the test data determined in Section 8, classify the
Test Method D 4318.
soil into the appropriate group or subgroup, or both, in
6. Sampling
accordance with Table 1 or Table 2. Use Fig. 1 to classify
6.1 Conduct field investigations and sampling in accordance silt-clay materials on the basis of liquid limit and plasticity
with one or more of the following procedures: index values.
TABLE 1 Classification of Soils and Soil-Aggregate Mixtures
Granular Materials Silt-Clay Materials
General Classification
(35 % or less passing No. 200) (More than 35 % passing No. 200)
A
Group Classification A-1 A-3 A-2 A-4 A-5 A-6 A-7
Sieve analysis, % passing:
No. 10 (2.00 mm) . . . . . . .
No. 40 (425 μm) 50 max 51 min . . . . .
No. 200 (75 μm) 25 max 10 max 35 max 36 min 36 min 36 min 36 min
Characteristics of fraction passing No. 40
(425 μm):
B
Liquid limit . . 40 max 41 min 40 max
B
Plasticity index 6 max N.P. 10 max 10 max 11 min41 min
11 min
General rating as subgrade Excellent to Good Fair to Poor
A
The placing of A-3 before A-2 is necessary in the “left to right elimination process” and does not indicate superiority of A-3 over A-2.
B
See Table 2 for values.
Reprinted with permission of American Association of State Highway and Transportation Officials
D 3282
TABLE 2 Classification of Soils and Soil-Aggregate Mixtures
Granular Materials Silt-Clay Materials
General Classification
(35 % or less passing No. 200) (More than 35 % passing No. 200)
A-1 A-2 A-7
Group classification A-3 A-4 A-5 A-6
A-7-5,
A-1-a A-1-b A-2-4 A-2-5 A-2-6 A-2-7
A-7-6
Sieve analysis, % passing:
No. 10 (2.00 mm) 50 max . . . . . . . . . .
No. 40 (425 μm) 30 max 50 max 51 min . . . . . . . .
No. 200 (75 μm) 15 max 25 max 10 max 35 max 35 max 35 max 35 max 36 min 36 min 36 min 36 min
Characteristics of fraction passing
No. 40 (425 μm):
Liquid limit . . 40 max 41 min 40 max 41 min 40 max 41 min 40 max 41 min
A
Plasticity index 6 max N.P. 10 max 10 max 11 min 11 min 10 max 10 max 11 min 11 min
Usual types of significant consti- Stone Fragments, Fine Silty or Clayey Gravel and Sand Silty Soils Clayey Soils
tuent materials Gravel and Sand Sand
General rating as subgrade Excellent to Good Fair to Poor
A
Plasticity index of A-7-5 subgroup is equal to or less than LL minus 30. Plasticity index of A-7-6 subgroup is greater than LL minus 30 (see Fig. 1).
Reprinted with permission of American Association of State Highway and Transportation Officials.
NOTE 1—A-2 soils contain less than 35 % finer than 200 sieve.
FIG. 1 Liquid Limit and Plasticity Index Ranges for Silt-Clay Materials
NOTE 5—All limiting values are shown as whole numbers. If fractional
numbers appear on test reports, convert to the nearest whole numbers for
the purpose of classification.
D 3282
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