Page 285 - Geotechnical Engineering Soil and Foundation Principles and Practice

Source: GEOTECHNICAL ENGINEERING
13 Compaction

13.1 HISTORICAL BACKGROUND

13.1.1 Paths of Least Resistance
Compaction is the oldest and most common method for soil stabilization, at first
being accomplished automatically as herd animals followed the same trails—some
of which are followed by the routes of modern highways.

Compaction has some obvious benefits. A compacted soil is harder, and can
support more weight and shed water better than the same soil that has
not been compacted. The extensive road system of the Roman Empire consisted
of stones laid flat on top of compacted soil. Roman road builders even
attempted to compact soil with elephants, which is not very efficient because
elephants prefer to step in the same tracks. The modern version of the elephant
walk is a ‘‘sheepsfoot roller’’ that emulates tracking by feet or hoofs, but does so
randomly.

13.1.2 The Twentieth Century

Compaction was largely intuitive and hit-or-miss until the 1930s when the
Los Angeles county engineer, R. R. Proctor, devised a laboratory test that
allowed systematizing and optimizing the compaction process. Proctor’s
procedure revolutionized the construction of roads and earth dams, respectively
the longest and the largest human-made structures in the world. Without these
control methods, costs would be higher and failures commonplace.

280 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2007 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.