Significance and Use
4.1 Dry density, as defined as “density of soil or rock” in Terminology and “bulk density” by soil scientists, can be used to convert the water fraction of soil from a mass basis to a volume basis and vise-versa. When particle density, that is, specific gravity (Test Methods ) is also known, dry density can be used to calculate porosity and void ratio (see ). Dry density measurements are also useful for determining degree of soil compaction. Since moisture content is variable, moist soil density provides little useful information except to estimate the weight of soil per unit volume, for example, pounds per cubic yard, at the time of sampling. Since soil volume shrinks with drying of swelling soils, bulk density will vary with moisture content. Hence, the water content of the soil should be determined at the time of sampling.
4.2 Densities (unit weights) of remolded/reconstituted specimens are commonly used to evaluate the degree of compaction of earthen fills, embankments, etc. Dry density values are usually used in conjunction with compaction curve values (Test Methods and ).
4.3 Density (unit weight) is one of the key components in determining the mass composition/phase relations of soil, see .
Note 1: The quality of the result produced by this standard 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 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice does not in itself assure reliable results. Reliable results depend on several factors; Practice provides a means of evaluating some of these factors.
1.1 These test methods describe two ways of determining the total/moist and dry densities (unit weights) of intact, disturbed, remolded, and reconstituted (compacted) soil specimens. Density (unit weight) as used in this standard means the same as “bulk density” of soil as defined by the Soil Science Society of America. Intact specimens may be obtained from thin-walled sampling tubes, block samples, or clods. Specimens that are remolded by dynamic or static compaction procedures may also be measured by these methods. These methods apply to soils that will retain their shape during the measurement process and may also apply to other materials such as soil-cement, soil-lime, soil-bentonite or solidified soil-bentonite-cement slurries. It is common for the density (unit weight) of specimens after removal from sampling tubes and compaction molds to be less than the value based on tube or mold volumes, or of in situ conditions. This is due to the specimen swelling after removal of lateral pressures.
1.1.1 Method A covers the procedure for measuring the volume of wax coated specimens by determining the quantity of water displaced.
220.127.116.11 This method only applies to specimens in which the wax will not penetrate the outer surface of the specimen.
1.1.2 Method B covers the procedure by means of the direct measurement of the dimensions and mass of a specimen, usually one of cylindrical shape. Intact and reconstituted/remolded specimens may be tested by this method in conjunction with strength, permeability (air/water) and compressibility determinations.
1.2 The values stated in SI units are to be regarded as the standard. The values stated in inch-pound units are approximate.
1.3 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice .
1.3.1 The method used to specify how data are collected, calculated, or recorded in this standard is not directly related to the accuracy with which the data can be applied in design or other uses, or both. How one applies the results obtained using this standard is beyond its scope.
1.4 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.
1.5 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.