ASTM D3282-15

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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: D3282 − 09 D3282 − 15
Standard Practice for
Classification of Soils and Soil-Aggregate Mixtures for
Highway Construction Purposes
This standard is issued under the fixed designation D3282; 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 practice covers 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 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are
mathematicalsieve designations are identified using the “standard” system in accordance with Specification E11conversions to SI
units that are provided for information only and are not considered standard., such as 75-mm and 75-μm, followed by the
“alternative” system of 3-in. and No. 200, respectively.
1.3 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 and health practices and determine the applicability of regulatory
limitations prior to use.
1.4 This practice offers a set of instructions for performing one or more specific operations. This practice cannot replace
education or experience and should be used in conjunction with professional judgment. Not all aspects of this practice may be
applicable in all circumstances. This practice is not intended to represent or replace the standard of care by which the adequacy
of a given professional service must be judged, nor should this practice be applied without consideration of a project’s many
unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the
ASTM consensus process.
2. Referenced Documents
2.1 ASTM Standards:
D420 Guide to Site Characterization for Engineering Design and Construction Purposes (Withdrawn 2011)
D421 Practice for Dry Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants
D422 Test Method for Particle-Size Analysis of Soils
D653 Terminology Relating to Soil, Rock, and Contained Fluids
D1140 Test Methods for Determining the Amount of Material Finer than 75-μm (No. 200) Sieve in Soils by Washing
D1452 Practice for Soil Exploration and Sampling by Auger Borings
D1586 Test Method for Penetration Test (SPT) and Split-Barrel Sampling of Soils
D1587 Practice for Thin-Walled Tube Sampling of Soils for Geotechnical Purposes
D2217D3740 Practice for Wet Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil ConstantsMini-
mum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and
Construction
Thispractice is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.07 on Identification and
Classification of Soils.
Current edition approved July 1, 2009Nov. 1, 2015. Published August 2009December 2015. Originally approved in 1973. Last previous edition approved in 20042009
ε1
as D3282 – 93 (2004)D3282 – 09. . DOI: 10.1520/D3282-09.10.1520/D3282-15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3282 − 15
D4318 Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
D4700 Guide for Soil Sampling from the Vadose Zone
D6913 Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
2.2 AASHTO Document:
M 145 The Classification of Soils and Soil Aggregate Mixtures for Highway Construction Purposes
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 The following terms are frequently used in this practice. These terms differ slightly from those given in Terminology
D653, but are used here to maintain consistency with common highway usage.
3.1.2 boulders—particles of rock with a minimum dimension of 305-mm (12-in.) or more.
3.1.3 cobbles—particles of rock with a minimum dimension of less than 305-mm (12-in.) and be retained on a 75-mm (3-in.)
sieve.
3.1.4 boulders and cobbles—gravel—particles of rock usually rounded by weathering or abrasion, that willthat will pass a
75-mm (3-in.) sieve and be retained on a 3-in. (75-mm) 2-mm (No. 10) sieve.
3.1.5 coarse sand—particles of rock or soil that will pass a No. 10 (2-mm)2-mm (No. 10) sieve and be retained on a No. 40
(425-μm)425-μm (No. 40) sieve.
3.1.6 fine sand—particles of rock or soil that will pass a No. 40 (425-μm)425-μm (No. 40) sieve and be retained on a No. 200
(75-μm)75-μm (No. 200) sieve.
3.1.5 gravel—particles of rock that will pass a 3-in. (75-mm) sieve and be retained on a No. 10 (2-mm) sieve.
3.1.7 silt-clay (combined silt and clay)—fine soil and rock particles that will pass a No. 200 (75-μm)75-μm (No. 200) sieve.
3.1.8 silty—fine-grained material that has a plasticity index of 10 or less.
3.1.9 clayey—fine-grained material that has a plasticity index of 11 or more.
NOTE 2—The terminology used above differs from terminology used in Terminology D653. The above terminology conforms in part to AASHTO
standard M 145.
3.1.10 irreversible mineral colloid, n—in soils, certain minerals such as feldspars, when weathered bind with water to form clay
minerals containing interlayer moisture, that when dried above 50°C, permanently lose this structural moisture.
Available from American Association of State Highway and Transportation Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,
http://www.transportation.org.
3.1.10.1 Discussion—
The dewatering process changes the nature of the mineralogy. This permanent dehydration has been shown to reduce plasticity,
increase particle size and may potentially skew the soil classification
3.1.11 stone fragment—a small piece of rock that has been mechanically broken from a larger stone.
NOTE 2—The terminology used above differs from terminology used in Terminology D653. The above terminology conforms in part to AASHTO
standard M 145.
4. Significance and Use
4.1 The practice described classifies soils from any geographic location into groups (including group indexes) based on the
results of prescribed laboratory tests to determine the particle-size characteristics, liquid limit, and plasticity index.
4.2 The assigning of a group symbol and group index can be used to aid in the evaluation of the significant properties of the
soil for highway and airfield purposes.
4.3 The various groupings of this classification system correlate in a general way with the engineering behavior of soils. Also,
in a general way, the engineering behavior of a soil varies inversely with its group index. Therefore, this practice provides a useful
first step in any field or laboratory investigation for geotechnical engineering purposes.
NOTE 3—The quality of the result produced by this standard is dependent upon 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 assure reliable results. Reliable
results depend on many factors; Practice D3740 provides a means of evaluation some of those factors.
5. Apparatus
5.1 Apparatus for Preparation of Samples—See PracticesPractice D421 or D2217.
5.2 Apparatus for Particle-Size Analysis—See Test Methods D1140, D422and , and D422D6913.
D3282 − 15
5.3 Apparatus for Liquid Limit and Plastic Limit Tests—See Test Methods D4318.
6. Sampling
6.1 Conduct field investigations and sampling in accordance with one or more of the following procedures:
6.1.1 Guide D420D4700,
6.1.2 Practice D1452,
6.1.3 Test Method D1586, and
6.1.4 Practice D1587.
7. Test Sample Samples and Testing Procedures
7.1 Test samples shall represent that portion of the field sample finer than the 3-in. (75-mm) sieve and shall be obtained as
follows:
7.1.1 Air-dry the field sample,
7.1.2 Weigh the field sample,
7.1.3 Separate the field sample into two fractions on a 3-in. (75-mm) sieve,
7.1.4 Weigh the fraction retained on the 3-in. (75-mm) sieve. Compute the percentage of plus 3-in. material in the field sample,
and note this percentage as auxiliary information, and
7.1.5 Thoroughly mix the fraction passing the 3-in. (75-mm) sieve and select the test samples.
NOTE 3—If visual examination indicates that no boulder size material is present, omit 7.1.3 and 7.1.4.
7.1 Prepare the test sample test specimens and perform testing in accordance with Practices D421 or D2217. Determine the
percentage of the sample finer than a No. 10 (2-mm) sieve.the following procedures:
NOTE 4—It is recommended that the method for wet preparation be used for soils containing organic matter or irreversible mineral colloids.
7.1.1 Test Samples and Testing for Particle-Size Analysis—Use either Test Methods D1140, D422 or D6913.
7.1.2 Test Samples and Testing for Liquid Limit and Plastic Limit Tests—Use Test Method D4318
8. Testing Procedure
8.1 Determine the percentage of the test sample finer than a No. 200 (75-μm) sieve in accordance with Test Methods D1140
or D422.
NOTE 5—For granular materials, the percentage of the sample finer than a No. 40 (425-μm) sieve must also be determined.
8.2 Determine the liquid limit and the plasticity index of a portion of the test sample passing a No. 40 (425-μm) sieve in
accordance with Test Methods D4318.
8. Classification Procedure
8.1 Using the test data determined by the methods in Section 87, classify the soil into the appropriate group or subgroup, or both,
in accordance with Table 1 or Table 2. Use Fig. 1 to classify silt-clay materials on the basis of liquid limit and plasticity index
TABLE 1 Classification of Soils and Soil-Aggregate Mixtures
Granular Materials Silt-Clay Materials
General Classification (35 % or less passing No. 200 (75 μm))35 % or (More than 35 % passing No. 200 (75 μm))More Than 35 %
Less Passing 75 μm (No. 200) Passing 75 μm (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) . . . . . . .
2.00 mm (No. 10) . . . . . . .
No. 40 (425 μm) 50 max 51 min . . . . .
425 μm (No. 40) 50 max 51 min . . . . .
No. 200 (75 μm) 25 max 10 max 35 max 36 min 36 min 36 min 36 min
75 μm (No. 200) 25 max 10 max 35 max 36 min 36 min 36 min 36 min
Characteristics of fraction passing No. 40
(425 μm):
Characteristics of fraction passing 425 μm
(No. 40):
B
Liquid limit . . 40 max 41 min 40 max 41 min
B
Plasticity index 6 max N.P. 10 max 10 max 11 min 11 min
B
Liquid Limit . . 40 max 41 min 40 max 41 min
B
Plasticity Index 6 max N.P. 10 max 10 max 11 min 11 min
General rating as subgrade Excellent to Good Fair to Poor
A
TheThe 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
SeeSee Table 2 for values.
Reprinted with permission of American Association of State Highway and Transportation Officials
D3282 − 15
TABLE 2 Classification of Soils and Soil-Aggregate Mixtures
Silt-Clay Materials
Granular Materials (More than 35 % passing No. 200 (75
General Classification
(35 % or less passing No. 200 (75 μm))35 % or Less Passing 75 μm (No. 200) μm))More Than 35 % Passing 75 μm (No.
200)
A-1 A-2 A-7
Group classificationClassification 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 . . . . . . . . . .
2.00 mm (No. 10) 50 max . . . . . . . . . .
No. 40 (425 μm) 30 max 50 max 51 min . . . . . . . .
425 μm (No. 40) 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
75 μm (No. 200) 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):
Characteristics of fraction passing
425 μm (No. 40):
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
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
Usual types of significant Stone Fragments, Fine Silty or Clayey Gravel and Sand Silty Soils Clayey Soils
constituent materials Gravel and Sand Sand
General rating as subgrade Excellent to Good Fair to Poor
A
PlasticityPlasticity 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.
values. Classification of materials in the various groups applies only to the fraction passing the 75-mm (3-in.) sieve. Boulders and
cobbles shall be excluded from the portion of the sample to be classified. However, the percentage of such material, if any, shall
be recorded.
8.1.1 All limiting values are shown as whole numbers. If fractional numbers appear on test reports, convert to the nearest whole
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