Density of Soil Specimens

Wet and dry density of soils are important values for geotechnical engineers in determining over-burden stresses, void ratios, maximum compaction and percent compaction of soils. Density value can also aid in the evaluation of soil strength and sensitivity.

While reporting on soil density has been part of routine laboratory testing for years, there have been no standards that outlined procedures for density testing. However, Subcommittee D18.03 on Texture, Plasticity and Density Characteristics of Soils has now developed such a standard, D7263, Test Methods for Laboratory Determination of Density (Unit Weight) of Soil Specimens. The subcommittee is part of ASTM International Committee D18 on Soil and Rock.

“The applications of D7263 span many soil tests, including much more sophisticated testing,” says Bill Quinn, laboratory manager, AECOM, and chair of Subcommittee D18.03. Quinn notes the following areas in which soil density testing plays a role:

• Soil density is routinely determined and reported when thin-walled tube samples, which are used to obtain an intact soil specimen with limited disturbance, are taken;
• Strength testing, such as unconfined compression, direct shear and triaxial tests, almost always reports soil density;
• Soil void ratio, which is important in strength testing, and soil porosity, important with ground-water studies, requires density determination in its calculations;
• Consolidation tests report soil density both before and after the test as a function of the measured soil settlement;
• Hydraulic conductivity tests (flow of water through a soil matrix) are influenced by void ratio and soil density; and
• Density of remolded or reconstituted specimens can serve to evaluate field conditions of back filling operations, embankments, landfill clay liners, etc.

Quinn says that all interested parties are welcome to join in the standards developing activities of D18.03. “This particular standard will require an interlaboratory testing program to enable a precision and bias statement to be developed,” says Quinn. “An adequate test program will be established, testing protocols will be outlined, laboratories need to be contacted for participation and the data obtained will need to be summarized.”

CONTACT

Technical Information: Bill Quinn, AECOM, Vernon Hills, Ill.

Phone: 847-279-2500

ASTM Staff: Robert Morgan

Phone: 610-832-9732