Expedient MESL Construction in Cold Weather
JEFFREY A. STARK, ROSA T. AFFLECK, AND SHERRI A. ORCHINO
BACKGROUND
INTRODUCTION
The MESL consists of six components: the lower
The purpose of this report is to document the
membrane, the upper membrane, membrane seal-
results of a field demonstration project using
ing materials, the membrane protection, the fill
Army engineers to construct membrane-encapsu-
soil, and the wearing surface (Fig. 1). At times the
lated soil layers (MESLs). The project took place in
membrane protection and wearing surface are
June 1997 at Fort Drum, New York, and was con-
combined. The MESL can be constructed with the
structed by the 365th Combat Heavy Engineering
side membranes exposed, or more commonly (and
Battalion from Pennsylvania.
preferably), with them protected. The MESL in Fig-
Road construction typically requires substan-
ure 1a is most expedient to construct and requires
tial amounts of gravel for the base course and the
borrow soil. However, its membranes are more
wearing surface. Sometimes gravel is in short
susceptible to damage and have a service life of
supply and alternative road building materials
just a few years or less. The MESL in Figure 1b can
and practices are required. One possible alterna-
use borrow soil or soil from the site on which it is
tive is to use MESLs, which make it possible to
placed; it is more time-consuming to construct, but
replace high-quality materials, such as gravel,
its membranes are protected from damage and it
with marginal-quality local materials.
has a potential service life of 20 years.
If silts and clays are compacted at or below
optimum moisture content, they can be very
strong, even strong enough to use as base or sub-
CURRENT PRACTICE
base materials. This strength, however, is lost as
Several MESLs have been constructed by the
they gain moisture. MESLs use waterproof mem-
Waterways Experiment Station (WES) and the
branes to encapsulate the silt and clays to prevent
Cold Regions Research and Engineering Labora-
moisture gain and the subsequent loss of
tory (CRREL) (Joseph and Webster 1971; Joseph et
strength, thus allowing these materials to be used
al. 1973; Sale et al. 1973; Schaefer 1973; Smith and
in place of gravel.
Karalius 1973; Webster 1974a, b; Webster and An-
Army engineers can use the MESL concept for
dress 1976; Smith 1978, 1979; Eaton and Berg 1980).
expedient construction of Main Supply Routes
These MESLs all followed the same general design
(MSRs) and other roads in the theater of opera-
procedure; the main differences are found in the
tions. MESLs could be used when gravel is in
membrane protection and wearing surface. Gravel
short supply or the haul distances are great, and
was used as a wearing surface on some of them
could be used to repair or construct short sections
and asphalt concrete on others. The materials used
of MSRs, to cross low areas, as approaches to
for the various components are listed below.
bridges, etc.
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