Soil type and soil properties
at the Raymark Superfund site, groundwater is
Since laboratory tests were not conducted on
not a factor. Instead, the concern is the infiltration
the materials currently in use for the pavement
of moisture, from either precipitation or snow-
structure at the Raymark site, thermal and hydrau-
melt, through the pavement surface into the base
lic properties were estimated from CRREL's soil
and subbase layers. To meet these criteria, all of
database. Therefore, the results of all of the simula-
the pavement structures were also modeled us-
tions are a best estimate from the limited amount of
ing a shallow (100-mm) water table and a deep
information on the material properties.
(2740-mm) water table.
Table 6 provides a summary of the soil types
The deep water table represents the current in-
currently in use for the Raymark Superfund site,
situ moisture content of the soil on site, and will
and the soil types used in all of the computer sim-
be referred to as either moist soil or low moisture
ulations. It should be noted that the model used a
content throughout this report. This is also a rea-
low to medium frost-susceptible material as the
sonable scenario for a new pavement structure.
graded aggregate base. The Tilcon common gran-
By locating the water table at a depth far from the
ular fill material was modeled as a well-graded
freezing front, the suction of moisture to the sur-
sandy material and the geosynthetic liner materi-
face during freezing is minimal. This scenario
als were modeled using a clay material. The clay
also assumes the pavement structure does not
was selected because for its low permeability and
permit infiltration of water through the asphalt
is most similar to the impermeable features of the
and into the underlying layers. The shallow water
geosynthetic liner materials.
table, on the other hand, represents an older pave-
Table 6. Summary of soils used in FROST model for simulation.
Material layer
Graded
Tilcon
Geosynthetic
Soil gas
Cement-
aggregate
common
liner
collection
treated
Soil parameters used
Asphalt
base
granular fill
materials
sand
waste
in FROST model
concrete
GW*
SM
CL
GP
SP
Soil density (g/cm3)
2.3
1.84
1.551
1.69
2.16
1.61
Soil porosity (cm3/cm3)
0.14
0.3311
0.419
0.374
0.2
0.436
Saturated hydraulic
conductivity (cm/hr)
2.1
4.7
1.6
0.14
0.46
8.1
Unfrozen volumetric
water content (cm3/cm3)
0.039
0.016189
0.03602
0.2916
0.0566
0.0198
* Modeled materials (Unified Soil Symbol).
The CRREL soil database does not contain any
ment where moisture infiltration occurs through
properties on stabilized materials. To model the
cracks in the surface layer. This scenario assumes
waste material, a poorly graded sand material
that the subsurface layers 100 mm below the sur-
was selected (denoted by the SP classification).
face are completely saturated, even during freez-
With respect to frost heave, the pores in the stabil-
ing. This scenario will be referred to as either the
ized material are filled with some form of stabil-
fully saturated or saturated case throughout this
izing agent. In the case of the Raymark Super-
report.
fund site, the stabilizing agent is cement. The
addition of the stabilizing agent makes the soil
Temperature data
impermeable and less prone to frost heave. The
In addition to the material properties, the air
poorly graded sand material was chosen because
temperature during the freezing season is re-
it had a high porosity that reduces capillary
quired as input for the model. The air tempera-
action in the soil, thereby reducing frost heave.
tures were selected based on the design freezing
index (DFI) (Johnson et al. 1975). Daily minimum
Water table depth
and maximum temperatures from 19651996
Typically, in a FROST simulation, the location
recorded from the Bridgeport Airport were used
of the water table below the pavement surface will
to determine the DFI. This weather station is the
have an impact on the computer results. However,
closest to the Raymark Superfund site in Strat-
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