Description and Identification of Soils (Visual-Manual Procedure) - Soil Properties: Testing, Measurement, and Evaluation - page 30

(3.2) Smooth the soil ball in the palm of one hand with the blade of
a knife or small spatula. Shake horizontally, striking the side of the
hand vigorously against the other hand several times. Note the re-
action of water appearing on the surface of the soil. Squeeze the
sample by closing the hand or pinching the soil between the fingers,
and note the reaction as none, slow, or rapid, in accordance with
the criteria in Table 3-9. The reaction is the speed with which water
appears while shaking and disappears while squeezing.

Table 3-9 Criteria for Describing Dilatancy [1]

Description Criteria

None No visible change in the specimen

Slow Water appears slowly on the surface of the specimen during

shaking and does not disappear or disappears slowly upon
squeezing

Rapid Water appears quickly on the surface of the specimen

during shaking and disappears quickly upon squeezing

(4) Toughness:

(4.1) Following the completion of the dilatancy test, the test speci-
men is shaped into an elongated pat and rolled by hand on a smooth
surface or between the palms into a thread about 1 ⁄ 8 in. (3 mm) in
diameter. (If the sample is too wet to roll easily, it should be spread
into a thin layer and allowed to lose some water by evaporation.)
Fold the sample threads and reroll repeatedly until the thread
crumbles at a diameter of about 1 ⁄ 8 in. The thread will crumble at a
diameter of 1 ⁄ 8 in. when the soil is near the plastic limit. Note the
pressure required to roll the thread near the plastic limit. Also, note
the strength of the thread. After the thread crumbles, the pieces
should be lumped together and kneaded until the lump crumbles.
Note the toughness of the material during kneading.

(4.2) Describe the toughness of the thread and lump as low,
medium, or high, in accordance with the criteria in Table 3-10.

Table 3-10 Criteria for Describing Toughness [1]

Description Criteria

Low Only slight pressure is required to roll the thread near the

plastic limit. The thread and the lump are weak and soft

Medium Medium pressure is required to roll the thread to near

the plastic limit. The thread and the lump have medium
stiffness

High Considerable pressure is required to roll the thread to

near the plastic limit. The thread and the lump have
very high stiffness

(5) Plasticity —On the basis of observations made during the
toughness test, describe the plasticity of the material in accordance
with the criteria given in Table 3-11.