Determining the Liquid Limit of Soil - Soil Properties: Testing, Measurement, and Evaluation - page 85

(At the end of the text, a blank copy of semilogarithmic graph paper is
included and may be photocopied as needed.) The liquid limit can be de-
termined from the flow curve by noting the water content that corresponds
to 25 drops. In this example, the liquid limit is observed to be 46.4%.

SUMMARY The primary result of the test performed is, of course, the value of the

liquid limit. As pointed out earlier in this chapter, it can be used to ap-
proximate the compression index [Eq. (7-1)] for normally consolidated
clays. In most cases, however, the liquid limit is determined and utilized
in association with the other Atterberg limits and the plasticity index,
all of which are used conjointly in soil identification and classification.
As mentioned previously, soil may be air dried prior to sieving
(through a No. 40 sieve) to obtain the liquid limit sample, but it should
not be oven dried. After sieving, care must be taken to ensure that the
sample is well mixed with water prior to placing it in the brass cup of
the liquid limit device. Entrapped air in the sample should be removed
prior to the test, as it may decrease the accuracy of the results obtained.
The test shall always proceed from the dryer to the wetter condi-
tion of the soil. In no case shall dried soil be added to the seasoned soil
being tested [5].

REFERENCES

[1] A. Atterberg, various papers published in the Int. Mitt. Bodenkd ., 1911,

1912.

[2] B. K. Hough, Basic Soils Engineering , 2d ed., The Ronald Press Company,

New York, 1969. Copyright © 1969 by John Wiley & Sons, Inc.

[3] Ralph B. Peck, Walter E. Hansen, and Thomas H. Thornburn, Foundation

Engineering , 2d ed., John Wiley & Sons, Inc., New York, 1974.

[4] A. W. Skempton, “Notes on the Compressibility of Clays,” Quart. J. Geol.

Soc. Lond., C , 119-135, 1944.

[5] 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.