1. Scope

1.1 This test method covers a quantitative determination of the distribution of particle sizes using both the sieve and sedimentation tests for soils having a maximum particle size of 25 mm. The sieve analysis method (Test Methods D6913) shall be used to determine the particle-size distribution (gradation) of the soil larger than the No. 200 (75 m) sieve. The sedimentation method (D7928) shall be used to determine the particle-size distribution (gradation) of the soil that is finer than the No. 200 (75 um) sieve and larger than about 0.2 um. 1.2 This test method can be used to evaluate both the coarse- and fine-grained portions of a soil having a wide range of particle sizes by combining the sedimentation results with the sieve analysis resulting in the complete gradation curve. This test method is applicable when all the material passes the 1 in. (25 mm) sieve and both a sieve and sedimentation analysis are needed to determine the particle-size distribution (gradation). Further, it is only applicable when the dry mass of the sample meets or exceeds the requirements of Table 1 and the finer portion is at least twice the mass requirements of Table 1. Failure to meet these mass requirements results in a nonconformance test result. NOTE 1-The significant digits recorded in this test method preclude obtaining the grain size distribution of materials that do not contain a significant amount of fines. For example, clean sands will not yield detectable amounts of silts and clay sized particles and, therefore, should not be tested with this test method. The minimum amount of fines in the sedimentation specimen is 15 g. 1.3 Square opening sieve criteria are used for determining the soil gradation between the 1 in. (25 mm) and the No. 200 (75 um) sieves, while a spherical settling diameter is used for sizes below 75 um. 1.4 The terms soil and material are used interchangeably throughout this test method. 1.5 This test method does not cover procurement of the sample or processing of the sample before obtaining the test specimen in any detail. It is assumed that the sample is obtained using appropriate methods and is representative of site materials or conditions. It is also assumed that the sample has been processed such that the sieve and sedimentation specimens accurately reflect the particle-size distribution (gradation) of the sample. 1.6 Sample Processing-Two preparation methods, moist and air dried, are provided to obtain the test specimen from the sample. The method selected will depend on the initial conditions of the soil, application of the test result, and the need for other testing on the sample. The method to be used may be specified by the requesting authority, otherwise the moist preparation method shall be the referee/preferred procedure. Moist preparation is important for soils whose properties are altered because o fair or oven drying. 1.7 This test method is not applicable for the following soils: 1.7.1 Soils containing fibrous peat that will change in particle size during the drying, washing, or sieving procedure. 1.7.2 Soils containing extraneous matter, such as organic solvents, oil, asphalt, wood fragments, or similar items. Such extraneous matter can affect the washing and sieving procedures (Note 2). NOTE 2-If extraneous matter, such as wood, can be easily removed by hand, it is permissible to do so. However, there may be cases in which the extraneous matter is being evaluated as part of the material and it should not be removed from the material. 1.7.3 Soils that contain cementitious components, such as cement, fly ash, lime, or other stabilization admixtures. 1.7.4 Soils with less than approximately 5 % fines. 1.8 This test method may not produce consistent test results within and between laboratories for the following soils. To test these soils, this test method shall be adapted or altered and these alterations documented. 1.8.1 Soils that flocculate during sedimentation. Such soils may need to be treated to reduce salinity or alter the pH of the suspension. 1.8.2 Friable soils in which the sieving processes change the gradation of the soil. Typical examples of these soils are some residual soils, most weathered shales, and some weakly cemented soils, such as hardpan, caliche, or coquina. 1.8.3 Soils that will not readily disperse such as glauconitic clays or some dried plastic clays. 1.9 Samples that are not soils but are made up of particles may be tested using this test method. The applicable sections above should be considered when deciding to use this test method. 1.10 Units-The values stated in SI units are to be regarded as the standard. Except the sieve designations, they are typically identified using the alternative system in accordance with Practice E11, such as 3 in. and No. 200, instead of the standard of 75 mm and 75 m, respectively. Reporting of test results in units other than SI shall not be regarded as nonconformance with this test method. The use of balances or scales recording pounds of mass (lbm) shall not be regarded as nonconformance with this standard. 1.11 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 unless superseded by this test method. 1.11.1 The procedures used to specify how data are collected/recorded and calculated in this test method are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the users objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this test method to consider significant digits used in analysis methods for engineering data. 1.12 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.13 This 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.

Keywords

hydrometer analysis; particle-size distribution (gradation); sedimentation; sieve analysis; grain size

Rationale

This standard is needed to provide a standard in which specifiers can refer to when they want both a hydrometer and sieve analysis on a soil sample. The other two standards are specific to either the hydrometer analysis or the sieve analysis independent of each other. This new combined method allows for on how to perform the testing when both analyses are required on a soil sample.

The title and scope are in draft form and are under development within this ASTM Committee.