ASTM D 2487 Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
ASTM D 2487 tiêu chuẩn ASTM về phân loại và gọi tên đất
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Scope
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Referenced Documents
2.1 ASTM Standards:
C 117 Test Method for Materials Finer Than 75-µm (No. 200) Sieve in Mineral Aggregates by Washing
C 136 Test Method for Sieve Analysis of Fine and Coarse Aggregates
C 702 Practice for Reducing Field Samples of Aggregate to Testing Size
D 420 Guide to Site Characterization for Engineering, Design and Construction Purposes
D 421 Practice for Dry Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants
D 422 Test Method for Particle-Size Analysis of Soils
D 653 Terminology Relating to Soil, Rock, and Contained Fluids
D 1140 Test Method for Amount of Material in Soils Finer than the No. 200 (75-µm) Sieve
D 2216 Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock
D 2217 Practice for Wet Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil Constants
D 2488 Practice for Description and Identification of Soils (Visual-Manual Procedure)
D 3740 Practice for Minimum Requirements for Agencies Engaged in the Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
D 4083 Practice for Description of Frozen Soils (VisualManual Procedure)
D 4318 Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
D 4427 Classification of Peat Samples by Laboratory Testing
E 11 Specification for Wire-Cloth Sieves for Testing Purposes
ASTM D 2487 Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
ASTM D 2487 tiêu chuẩn ASTM về phân loại và gọi tên đất
- Terminology
3.1 Definitions—Except as listed below, all definitions are in accordance with Terminology D 653.
NOTE 4—For particles retained on a 3-in. (75-mm) U.S. standard sieve, the following definitions are suggested:
Cobbles—particles of rock that will pass a 12-in. (300-mm) square opening and be retained on a 3-in. (75-mm) U.S. standard sieve, and Boulders—particles of rock that will not pass a 12-in. (300-mm) square Opening
3.1.1 clay—soil passing a No. 200 (75-µm) U.S. standard sieve that can be made to exhibit plasticity (putty-like properties) within a range of water contents and that exhibits considerable strength when air dry. For classification, a clay is a fine-grained soil, or the fine-grained portion of a soil, with a plasticity index equal to or greater than 4, and the plot of plasticity index versus liquid limit falls on or above the “A” line.
3.1.2 gravel—particles of rock that will pass a 3-in. (75- mm) sieve and be retained on a No. 4 (4.75-mm) U.S. standard sieve with the following subdivisions:
Coarse—passes 3-in. (75-mm) sieve and retained on 3⁄4-in. (19-mm) sieve, and
Fine—passes 3⁄4-in. (19-mm) sieve and retained on No. 4 (4.75-mm) sieve.
3.1.3 organic clay—a clay with sufficient organic content to influence the soil properties. For classification, an organic clay is a soil that would be classified as a clay except that its liquid limit value after oven drying is less than 75 % of its liquid limit value before oven drying.
3.1.4 organic silt—a silt with sufficient organic content to influence the soil properties. For classification, an organic silt is a soil that would be classified as a silt except that its liquid limit value after oven drying is less than 75 % of its liquid limit value before oven drying.
3.1.5 peat—a soil composed of vegetable tissue in various stages of decomposition usually with an organic odor, a
dark-brown to black color, a spongy consistency, and a texture ranging from fibrous to amorphous.
3.1.6 sand—particles of rock that will pass a No. 4 (4.75- mm) sieve and be retained on a No. 200 (75-µm) U.S. standard sieve with the following subdivisions:
Coarse—passes No. 4 (4.75-mm) sieve and retained on No. 10 (2.00-mm) sieve
Medium—passes No. 10 (2.00-mm) sieve and retained on No. 40 (425-µm) sieve, and
Fine—passes No. 40 (425-µm) sieve and retained on No. 200 (75-µm) sieve.
3.1.7 silt—soil passing a No. 200 (75-µm) U.S. standard sieve that is nonplastic or very slightly plastic and that exhibits little or no strength when air dry. For classification, a silt is a fine-grained soil, or the fine-grained portion of a soil, with a plasticity index less than 4 or if the plot of plasticity index versus liquid limit falls below the “A” line
3.2 Definitions of Terms Specific to This Standard:
3.2.1 coeffıcient of curvature, Cc—the ratio (D30)2/ (D10 3 D60), where D60, D30, and D10 are the particle sizes
corresponding to 60, 30, and 10 % finer on the cumulative particle-size distribution curve, respectively.
3.2.2 coeffıcient of uniformity, Cu—the ratio D60/D10, where D60 and D10 are the particle diameters corresponding to 60 and 10 % finer on the cumulative particle-size distribution curve, Respectively
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Summary
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Significance and Use
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Apparatus
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Sampling
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Classification of Peat
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Preparation for Classification
ASTM D 2487 Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
ASTM D 2487 tiêu chuẩn ASTM về phân loại và gọi tên đất
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Preliminary Classification Procedure
10.1 Class the soil as fine-grained if 50 % or more by dry weight of the test specimen passes the No. 200 (75-µm) sieve and follow Section 3.1.2.
10.2 Class the soil as coarse-grained if more than 50 % by dry weight of the test specimen is retained on the No. 200
(75-µm) sieve and follow Section 12
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Procedure for Classification of Fine-Grained Soils:
(50 % or more by dry weight passing the No. 200 (75- µm) sieve)
11.1 The soil is an inorganic clay if the position of the plasticity index versus liquid limit plot, Fig. 4, falls on or above the “A” line, the plasticity index is greater than 4, and the presence of organic matter does not influence the liquid limit as determined in 11.3.2.
NOTE 7—The plasticity index and liquid limit are determined on the minus No. 40 (425 µm) sieve material.
11.1.1 Classify the soil as a lean clay, CL, if the liquid limit is less than 50. See area identified as CL on Fig. 4.
11.1.2 Classify the soil as a fat clay, CH, if the liquid limit is 50 or greater. See area identified as CH on Fig. 4
11.1.3 Classify the soil as a silty clay, CL-ML, if the position of the plasticity index versus liquid limit plot falls on
or above the “A” line and the plasticity index is in the range of 4 to 7. See area identified as CL-ML on Fig. 4.
11.2 The soil is an inorganic silt if the position of the plasticity index versus liquid limit plot, Fig. 4, falls below the
“A” line or the plasticity index is less than 4, and presence of organic matter does not influence the liquid limit as determined in 11.3.2.
11.2.1 Classify the soil as a silt, ML, if the liquid limit is less than 50. See area identified as ML on Fig. 4.
11.2.2 Classify the soil as an elastic silt, MH, if the liquid limit is 50 or greater. See area identified as MH on Fig. 4.
11.3 The soil is an organic silt or clay if organic matter is present in sufficient amounts to influence the liquid limit as determined in 11.3.2
11.3.1 If the soil has a dark color and an organic odor when moist and warm, a second liquid limit test shall be performed on a test specimen which has been oven dried at 110 6 5°C to a constant weight, typically over night.
11.3.2 The soil is an organic silt or organic clay if the liquid limit after oven drying is less than 75 % of the liquid limit of the original specimen determined before oven drying (see Procedure B of Practice D 2217).
11.3.3 Classify the soil as an organic silt or organic clay, OL, if the liquid limit (not oven dried) is less than 50 %.
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Procedure for Classification of Coarse-Grained Soils
(more than 50 % retained on the No. 200 (75-µm) sieve)
12.1 Class the soil as gravel if more than 50 % of the coarse fraction [plus No. 200 (75-µm) sieve] is retained on the No. 4 (4.75-mm) sieve.
12.2 Class the soil as sand if 50 % or more of the coarse fraction [plus No. 200 (75-µm) sieve] passes the No. 4
(4.75-mm) sieve.
12.3 If 12 % or less of the test specimen passes the No. 200 (75-µm) sieve, plot the cumulative particle-size distribution,
Fig. 5, and compute the coefficient of uniformity, Cu, and coefficient of curvature, Cc, as given in Eqs 1 and 2.
Cu = D60/D10
Cc=(D30)2/(D10xD60)
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Report
13.1 The report should include the group name, group symbol, and the results of the laboratory tests. The particle-size distribution shall be given in terms of percent of gravel, sand, and fines. The plot of the cumulative particle-size distribution curve shall be reported if used in classifying the soil. Report appropriate descriptive information according to the procedures in Practice D 2488. A local or commercial name or geologic interpretation for the material may be added at the end of the descriptive information if identified as such. The test procedures used shall be referenced
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Precision and Bias
14.1 Criteria for acceptability depends on the precision and bias of Test Methods D 422, D 1140 and D 4318.
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Keywords
15.1 Atterberg limits; classification; clay; gradation; gravel;
laboratory classification; organic soils; sand; silt; soil classification; soil tests
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ASTM D 2487 Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)
ASTM D 2487 tiêu chuẩn ASTM về phân loại và gọi tên đất
