The gradation of the soil is used for classification in accordance with Practice D 2487
The gradation (particle-size distribution) curve is used to calculate the coefficient of uniformity and the coefficient of curvature.
Selection and acceptance of fill materials are often based on gradation. For example, highway embankments, backfills, and earthen dams may have gradation requirements.
The gradation of the soil often controls the design and quality control of drainage filters, and ground-water drainage.
Selection of options for dynamic compaction and grouting is related to gradation of the soil.
The gradation of a soil is an indicator of engineering properties. Hydraulic conductivity, compressibility, and shear strength are related to the gradation of the soil. However, engineering behavior is dependent upon many factors (such as effective stress, stress history, mineral type, structure, plasticity, and geologic origins) and cannot be based solely upon gradation.
Note 18212;The quality of the result produced by these test methods 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 D 3740
1.1 Soils consist of particles with various shapes and sizes. This test method is used to separate particles into size ranges and to determine quantitatively the mass of particles in each range. These data are combined to determine the particle-size distribution (gradation). This test method uses a square opening sieve criterion in determining the gradation of soil between the 3-in. (75-mm) and No. 200 (75-µm) sieves.
1.2 The terms, soils and material, are used interchangeably throughout the standard.
1.3 In cases where the gradation of particles larger than 3 in. (75 mm) sieve is required, Test Method D 5519
1.4 In cases where the gradation of particles smaller than No. 200 (75-µm) sieve is required, Test Method D 422
1.5 Typically, if the maximum particle size is equal to or less than 4.75 mm (No. 4 sieve), then single-set sieving is applicable. Furthermore, if the maximum particle size is greater than 4.75 mm (No. 4 sieve) and equal to or less than 9.5 mm (3/8-in sieve), then either single-set sieving or composite sieving is applicable. Finally, if the maximum particle size is equal to or greater than 19.0 mm (3/4-in sieve), composite sieving is applicable. For special conditions see 10.3.
1.6 Two test methods are provided in this standard. The methods differ in the significant digits recorded and the size of the specimen (mass) required. The method to be used may be specified by the requesting authority; otherwise Method A shall be performed.
1.6.1 Method A8212;The percentage (by mass) passing each sieve size is recorded to the nearest 1 %. This method must be used when performing composite sieving. For cases of disputes, Method A is the referee method.
1.6.2 Method B8212;The percentage (by mass) passing each sieve size is recorded ......
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