Determining the Density and Unit Weight of Soil in Place by the Sand-Cone Method - Soil Properties: Testing, Measurement, and Evaluation - page 199

The general procedure for determining in-place soil density/unit weight
is to find the mass/weight and volume of an in-place soil sample, from
which the density/unit weight can be computed. In the sand-cone
method, a quantity of soil is removed from the ground or compacted fill.
The mass of the soil removed is determined directly, whereas the volume
is obtained indirectly by finding how much sand is required to fill the
hole. The mass/weight of soil removed from the hole divided by the vol-
ume gives the density/unit weight.
The actual step-by-step procedure is as follows (ASTM D 1556-00 [1]):

PROCEDURE

(1) Select a location/elevation that is representative of the area to
be tested, and determine the density of the soil in-place as follows:

(1.1) Inspect the cone apparatus for damage, free rotation of the
valve, and properly matched baseplate. Fill the cone container with
conditioned sand for which the bulk-density has been determined
and determine the total mass.

(1.2) Prepare the surface of the location to be tested so that it is a
level plane. The base plate may be used as a tool for striking off the
surface to a smooth level plane.

(1.3) Seat the base plate on the plane surface, making sure there is
contact with the ground surface around the edge of the flanged cen-
ter hole. Mark the outline of the base plate to check for movement
during the test, and if needed, secure the plate against movement
using nails pushed into the soil adjacent to the edge of the plate, or
by other means, without disturbing the soil to be tested.

(1.4) In soils where leveling is not successful, or surface voids re-
main, the volume horizontally bounded by the funnel, plate, and
ground surface must be determined by a preliminary test. Fill the
space with sand from the apparatus, determine the mass of sand
used to fill the space, refill the apparatus, and determine a new ini-
tial mass of apparatus and sand before proceeding with the test.
After this measurement is completed, carefully brush the sand
from the prepared surface (see Note 1).

Note 1 —A second calibrated apparatus may be taken to the
field when this condition is anticipated (instead of refilling
and making a second determination). The procedure in (1.4)
may be used for each test when the best possible accuracy is
desired; however, it is usually not needed for most production
testing where a relatively smooth surface is obtainable.

(1.5) The test hole volume will depend on the anticipated maximum
particle size in the soil to be tested. Test hole volumes are to be as
large as practical to minimize the errors and shall not be less than
the volumes indicated in Table 14-1. A hole depth should be selected
that will provide a representative sample of the soil. For construction
control, the depth of the hole should approximate the thickness of