Determining the Unconfined Compressive Strength of Cohesive Soil - Soil Properties: Testing, Measurement, and Evaluation - page 327

[B] Compression Data

Proving ring calibration 6,000 lb in.

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Deformation Dial, Δ H (in.) Proving Ring Dial (in.)

0.000 0.0000

0.025 0.0024

0.050 0.0058

0.075 0.0086

0.100 0.0116

0.125 0.0150

0.150 0.0176

0.175 0.0208

0.200 0.0224

0.225 0.0232

0.240 0.0224

0.260 0.0198

All of these data are shown on forms prepared for recording both
collected laboratory data and computed results (see pages 329 and 330).
At the end of the chapter, two blank copies of these forms are included
for the reader's use.
With the data listed, computations would proceed as follows:

[A] Specimen Parameters

The height-to-diameter ratio is 5.98/2.50, or 2.4, which is between 2 and
2.5 and, therefore, acceptable. The specimen's initial area, A 0 , and vol-
ume are easily computed as follows:

2

A 0 p D 2

2.50 p 1 2

4.91 in . 2

4 4

Volume A 0 H 0 4.91 5.98 29.36 in. 3 1 21 2 1 21 2

With the specimen's mass and volume known, its wet unit weight

γ wet

can be determined:

1,728 991.50 ft 3 128.6 lb g wet

29.36 453.6

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(The numbers 1,728 and 453.6 are conversion factors: 1,728 in. 3 1 ft 3 ;

453.6 g 1 lb.)

The water content of the specimen can be computed as follows (see
Chapter 4):

383.41 326.78
326.78 50.56 100 20.5%

w

Finally, the dry unit weight

γ dry can be computed:

128.6
20.5 100 100 106.7 lb

g wet
w 100 100

g dry ft 3 >