Since maximum density varies only slightly with
variations in the cement content, only the median value
is used in preparing specimens for the test. Additional
information on selecting the cement content can be
found in chapter 5 of NAVFAC MO-330.
The procedures for determining the OMC are
similar to those described in chapter 13 of this
TRAMAN with the following exceptions:
1. Compaction is performed on five layers of
approximately equal thickness to result in a total
compacted depth of 5 inches.
2. Each layer is compacted by 25 uniformly spaced
blows using a 10-pound tamper dropped from a height
of 18 inches.
. The wet-dry test (ASTM D 559) determines the
cement content for soil-cement mixtures used in
nonfrost areas. The objective is to determine the
minimum amount of cement that will enable the
soil-cement mixture to pass the test. For the test,
specimens are molded using the OMC and the cement
contents described above for different soil
classifications. Use the procedure for the OMC
determination to mold the specimens, and take a
750-gram sample from the second layer for a moisture
determination. Cure the specimens for 7 days in high
humidity. After curing, the specimens are weighed and
submerged in tap water at room temperature for 5 hours.
They are then oven-dried for 42 hours at 160°F. Material
loosened by wetting and drying is then removed using
two firm strokes of a wire brush. After this, you then
reweigh the specimens and subtract the new weight
from the old weight to determine the amount of
disintegration (soil-cement loss) that occurred during
the cycle. The process is repeated for a total of 12 cycles.
A passing grade ranges from 14-percent loss for sandy
or gravelly soils down to 7 percent for clayey soil.
Additional information about the wet-dry test and
an example of determining the soil-cement loss can be
found in NAVFAC MO-330.
. The freeze-thaw test (ASTM D 560) determines
the cement content for soil-cement mixtures used in
areas subject to frost action due to repeated freezing and
thawing. As in the wet-dry test, the objective of the
freeze-thaw test is to determine the minimum amount of
cement that enables the mixture to pass the test. For the
test, specimens are molded and cured in the same
manner as the wet-dry test. After 7 days of curing, the
specimens are placed on moist blotters and are
refrigerated for 24 hours at -10°F. They are then thawed
in a moist atmosphere at 70°F for 23 hours. Then you
brush the specimens as described above and, if
necessary, remove any half-loose scales using a
sharp-pointed instrument. After 12 cycles, the
specimens are oven-dried and weighed. The soil-
cement loss is determined the same way as in the
wet-dry test. Again, passing grades range from
14-percent loss for sandy or gravelly soils down to
7 percent for clayey soil.
For additional information regarding the
freeze-thaw test, you should refer to NAVFAC MO-330.
The principal requirement of a hardened
soil-cement mixture is to withstand exposure to the
elements. Strength is a requirement also; however,
most soil-cement mixtures that have adequate
resistance to the elements also have adequate
strength. In the ranges of cement contents producing
results meeting the requirements above, the strength
of soil-cement specimens tested in compression at
various ages should increase with age and with
increases in cement. A sample that has an unconfined
compressive strength of approximately 300 pounds
per square inch (psi) after curing 7 days and shows
increasing strength with age can be considered
adequately stabilized. NAVFAC MO-330 has the
procedures that you should follow when performing
unconfined compression tests.
For a discussion of modified mix design for sandy
soils and for approximate and rapid test procedures that
you can use when complete testing is impracticable, you
should refer to NAVFAC MO-330. Construction
methods using soil-cement can be found in Military,
Soils Engineering, FM5-541, and in commercial
publications, such as Moving the Earth, by Herbert L.
Nichols, Jr., and various publications from the Portland
Bituminous soil stabilization refers to a process by
which a controlled amount of bituminous material is
thoroughly mixed with an existing soil or aggregate
material to form a stable base or wearing surface.
Bitumen increases the cohesion and load-bearing
capacity of the soil and renders it resistant to the action
The recommended soil gradations for subgrade and
base or subbase course materials are shown in