ASTM D6913/D6913M-17

5.1The gradation of the soil is used for classification in accordance with Practice D2487.

5.2The gradation (particle-size distribution) curve is used to calculate the coefficient of uniformity and the coefficient of curvature.

5.3Selection and acceptance of fill materials are often based on gradation. For example, highway embankments, backfills, and earthen dams may have gradation requirements.

5.4The gradation of the soil often controls the design and quality control of drainage filters, and groundwater drainage.

5.5Selection of options for dynamic compaction and grouting is related to gradation of the soil.

5.6The 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.

1.1Soils 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-m) sieves.

1.2The terms, soils and material, are used interchangeably throughout the standard.

1.3In cases where the gradation of particles larger than 3 in. (75 mm) sieve is needed, Test Method D5519 may be used.

1.4In cases where the gradation of particles smaller than No. 200 (75-m) sieve is needed, Test Method D7928 may be used.

1.5Typically, 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.

1.6Two 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.

1.7This test method does not cover, in any detail, procurement of the sample. It is assumed that the sample is obtained using appropriate methods and is representative.

1.8Sample ProcessingThree procedures (moist, air dry, and oven dry) are provided to process the sample to obtain a specimen. The procedure selected will depend on the type of sample, the maximum particle-size in the sample, the range of particle sizes, the initial conditions of the material, the plasticity of the material, the efficiency, and the need for other testing on the sample. The procedure may be specified by the requesting authority; otherwise the guidance given in Section 10 shall be followed.

1.9This test method typically requires two or three days to complete, depending on the type and size of the sample and soil type.

1.10This test method is 1.10.1Soils containing fibrous peat that will change in particle size during the drying, washing, or sieving procedure.

1.10.2Soils containing extraneous matter, such as organic solvents, oil, asphalt, wood fragments, or similar items. Such extraneous matter can affect the washing and sieving procedures.

1.10.3Materials that contain cementitious components, such as cement, fly ash, lime, or other stabilization admixtures.

1.11This test method may not produce consistent test results within and between laboratories for the following soils and the precision statement does not apply to them.

1.12Some materials that are not soils, but are made up of particles may be tested using this method. However, the applicable sections above should be used in applying this standard.

1.13All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026, unless superseded by this test method.

1.14UnitsThe dimensional values stated in either SI units or inch-pound units are to be regarded as standard, such as 200-mm or 8-in. diameter sieve. Except, the sieve designations are typically identified using the alternative system in accordance with Practice E11, such as 3 in. and No. 200, instead of the standard system of 75 mm and 75 m, respectively. Only the SI units are used for mass determinations, calculations, and reported results. However, the use of balances or scales recording pounds of mass (lbm) shall not be regarded as nonconformance with this standard.

1.15A summary of the symbols used in this test method is given in Annex A1.

1.16This 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.

1.17Table of ContentsAll tables and figures appear at the end of this standard.

1.18This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.