Determining the Moisture Content of Soil and Rock by Mass (Conventional Oven Method) - Soil Properties: Testing, Measurement, and Evaluation - page 41

Table 4-1 Minimum Requirements for Mass of Test Specimen, and Balance Readability

Maximum Particle Size Method A Method B

(100 % Passing) Water Content Recorded to 1 % Water Content Recorded to 0.1 %

SI Unit Alternative Specimen Balance Specimen Balance

Sieve Size Sieve Size Mass Readability (g) Mass (g) Readability (g)

75.0 mm 3 in 5 kg 10 50 g 10

37.5 mm 1 1 ⁄ 2 in 1 kg 10 10 g 10

19.0 mm

3
⁄ 4 in. 250 g 1 2.5 g 1

9.5 mm

3
⁄ 3 in. 50 g 0.1 500 g 0.1

4.75 mm No. 4 20 g 0.1 100 g 0.1

2.00 mm No. 10 20 g 0.1 20 g 0.01

(3) Using a test specimen smaller than the minimum indicated in
(2) requires discretion, though it may be adequate for the purposes
of the test. Any specimen used not meeting these requirements
shall be noted on the test data forms or test data sheets.

(4) When working with a small (less than 200 g) specimen con-
taining a relatively large gravel particle, it is appropriate not to in-
clude this particle in the test specimen. However, any discarded
material shall be described and noted on the test data forms or test
data sheets.

(5) For those samples consisting entirely of intact rock or gravel-
size aggregate, the minimum specimen mass shall be 500 g. Repre-
sentative portions of the sample may be broken into smaller
particles. The particle size is dictated by the specimen mass, the
container volume, and the balance being used to determine con-
stant mass, see No. (4) under the Section “Procedure.” Specimen
masses as small as 200 g may be tested if water contents of only two
significant digits are acceptable.

(1) When the test specimen is a portion of a larger amount of mate-
rial, the specimen must be selected to be representative of the water
condition of the entire amount of material. The manner in which the
test specimen is selected depends on the purpose and application of
the test, type of material being tested, the water condition, and the
type of sample (from another test, bag, block, and the like).

TEST SPECIMEN
SELECTION [1]

(2) For disturbed samples, such as trimmings, bag samples, etc.,
obtain the test specimen by one of the following methods (listed in
order of preference):

(2.1) If the material is such that it can be manipulated and handled
without significant moisture loss and segregation, the material
should be mixed thoroughly, and then select a representative portion
using a scoop of a size that no more than a few scoopfuls are required
to obtain the proper size of specimen defined by No. (2) under the Sec-
tion “Test Specimen.” Combine all the portions for the test specimen.