Determining the Density and Unit Weight of Soil in Place by the Sand-Cone Method - Soil Properties: Testing, Measurement, and Evaluation - page 206

w 21.6 %

1,854

M 5 1,525 g

1 0.01 21 21.6 100 2

M 6 M 7
r 1

V (14-6)

M 6 8,045 4,867 3,178 g

M 7 1,667 g

r 1 1.565 g

mL

>

3,178 1,667

1.565

V 965.5 mL

M 5
V

(14-7)

r 2

1,525
965.5 1.579 g

r 2 > mL

g 2 62.43 r 2

(14-8)

ft 3

62.43 1.579 98.6 lb

g 2 1 21 2 >

All data—both given and calculated—are presented on the form
shown on pages 207-208. (At the end of the chapter, two blank copies of
this form are included for the reader's use.) Careful study of this form
should facilitate understanding of the calculations required to deter-
mine in-place dry density and unit weight.

Because test holes are relatively small, it is important that no soil be
lost while excavating and that volume determinations be done very
carefully to ensure accurate evaluations of in-place density. To get an
accurate moisture content of the soil, excavation should be done as
quickly as possible. Also, vibration of the ground and the jar should be
avoided to prevent too much sand from entering the hole.
As explained in the introduction to this chapter, unit weight of soil
in place is used primarily in documenting field compaction. The sand-
cone method provides a convenient and accurate means of determining
in-place density and unit weight, although the volume of the sample is
determined indirectly. An alternative procedure, the rubber-balloon
method, makes a more direct measurement of the volume of the sample.
This procedure is described in Chapter 15.

SUMMARY

REFERENCE [1] ASTM, 2007 Annual Book of ASTM Standards , West Conshohocken, PA,

2007. Copyright, American Society for Testing and Materials, 100 Barr
Harbor Drive, West Conshohocken, PA 19428-2959. Reprinted with per-
mission.