Determining the Moisture Content of Soil and Rock by Mass (Conventional Oven Method) - Soil Properties: Testing, Measurement, and Evaluation - page 42

(2.2) If the material is such that it cannot be thoroughly mixed
and/or split, form a stockpile of the material, mixing as much as
possible. Take at least five portions of material at random locations
using a sampling tube, shovel, scoop, trowel, or similar device
appropriate to the maximum particle size present in the material.
Combine all the portions for the test specimen.

(2.3) If the material or conditions are such that a stockpile cannot
be formed, take as many portions of the material as practical using
random locations that will best represent the moisture condition.
Combine all the portions for the test specimen.

(3) Intact samples, such as block, tube, split barrel, and the like,
obtain the test specimen by one of the following methods depend-
ing on the purpose and potential use of the sample.

(3.1) Using a knife, wire saw, or other sharp cutting device, trim
the outside portion of the sample a sufficient distance to see if the
material is layered and to remove material that appears more dry
or more wet than the main portion of the sample. If the existence of
layering is questionable, slice the sample in half. If the material is
layered, see No. (3.3).

(3.2) If the material is not layered, obtain the specimen meeting
the mass requirements in No. (2) under the Section “Test Speci-
men” by: (1) taking all or one-half of the interval being tested;
(2) trimming a representative slice from the interval being tested;
or (3) trimming the exposed surface of one-half or from the inter-
val being tested.

Note 1 —Migration of moisture in some cohesionless soils may
require that the full section be sampled.

(3.3) If a layered material (or more than one material type) is
encountered, select an average specimen, or individual specimens,
or both. Specimens must be properly identified as to location or
what they represent and appropriate remarks entered on the test
data forms or test data sheets.

Determination of moisture content of soil is actually quite simple. As
indicated by Eq. (4-1), it is necessary only to determine the (1) mass
of water in the soil sample and (2) mass of soil solids in the same sam-
ple. This is easily done by determining the mass of the moist soil sam-
ple, drying the sample to remove moisture, and then measuring the
mass of the remaining oven-dried sample. The mass of the remaining
oven-dried sample is, of course, the mass of soil solids in the sample.
The difference between that mass and the mass of the original moist
sample is the mass of water in the original sample. Substituting
these values into Eq. (4-1) will give the desired moisture content of
the soil.

PROCEDURE