ASTM D5550-23

5.1?The specific gravity value is used in many phase relation equations to determine relative volumes of particle, water, and gas mixtures.

5.2?The term soil particle typically refers to a naturally occurring mineral grain that is not readily soluble in water. Therefore, the specific gravity of soils that contain extraneous matter (such as cement, lime, and the like) or water-soluble material (such as salt) must be corrected for the precipitate that forms on the test specimen after drying. If the precipitate has a specific gravity less than the parent soil grains, the uncorrected test result will be too low. If the precipitate has a higher specific gravity, then the uncorrected test value will be too high.

5.3?Heating during drying may diagenetically alter the structure of some clay minerals.3 Therefore caution should be exercised if the mineral composition of a clay test specimen is going to be determined after drying. It is possible to dry the test specimen at a lower temperature. However, the effect on water content4 and hence specific gravity should be investigated. In addition, some materials other than clay may be affected by drying at 110?C, such as gypsum, soils containing organics, fly ash containing residual coal, island sands. Test Method D2216 includes recommendations for drying gypsum using a lower temperature, such as 60?C.

1.1?This test method covers the determination of the specific gravity of soil solids by means of a gas pycnometer. Particle size is limited by the dimensions of the test specimen container of the particular pycnometer being used.

1.2?Test Method D854 may be used instead of or in conjunction with this test method for performing specific gravity tests on soils. Note that Test Method D854 does not require the specialized test apparatus needed by this test method. However, Test Method D854 may not be used if the test specimen contains matter that can readily dissolve in water, whereas this test method does not have that limitation.

1.3?All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.

1.4?UnitsThe values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only and are not considered standard.

1.5?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.

1.6?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.