Testing of Materials from the Minnesota
Cold Regions Pavement Research Test Facility
SUSAN R. BIGL AND RICHARD L. BERG
and 566. We alternatively refer to these same re-
INTRODUCTION
spective materials as samples 1171, 1193, 1206,
This is one of four reports that describe work
and 1232.
conducted by the U.S. Army Cold Regions Re-
The base and subbase materials tested included
search and Engineering Laboratory related to the
the class 3 special subbase, a material with a high
Minnesota Road Research Project (Mn/ROAD)
percentage of fines, and the class 6 special base,
constructed by the Minnesota Department of Trans-
which has a relatively small amount of fines. The
portation (Mn/DOT). The emphasis of this report
"special" specifications for the base and subbase
is to summarize information resulting from vari-
materials were established specifically for Mn/
ous laboratory tests conducted to characterize ma-
ROAD, and are different from Mn/DOT's normal
terials from Mn/ROAD. Another report discusses
base/subbase specifications. Class 3 special and
the results of resilient modulus testing of the Mn/
class 6 special materials were initially transmitted
ROAD materials (Berg et al. 1996). A third report
to us as separate size fractions. We created some
describes computer modeling that applies the
samples by mixing these fractions to achieve gra-
mechanistic design procedure under development
dations near the center of the limits specified by
at CRREL to some of the Mn/ROAD test sections
Mn/DOT; these samples are referred to as "blend-
(Bigl and Berg 1996a), and the final report sum-
ed" materials. Subsequently, we received samples
marizes information in the first three reports (Bigl
of these materials drawn from stockpiles created
and Berg 1996b).
for Mn/ROAD. We refer to these as "stockpile"
The laboratory tests discussed here include frost
samples.
susceptibility (along with the physical properties:
Mn/DOT also used two other subbase materials
grain-size distribution, specific gravity, optimum
at the Mn/ROAD facility, termed class 4 special
density and moisture content at specified com-
and class 5 special, which have percentages of
pactive efforts, Atterberg limits, and organic con-
fines that lie intermediate between class 3 special
tent), hydraulic properties, and unfrozen moisture
and class 6 special. Testing of these materials was
content.
accomplished under a later contract. However, in
order to model the predicted damage of test sec-
tions that include class 4 special and class 5 spe-
Materials received
Laboratory testing was performed on samples
cial materials, their behavior was approximated
of the clay subgrade from beneath the Mn/ROAD
using data from materials tested during prior stud-
site and on two of the materials that were used as
ies that most closely matched their specified size
base and subbase in the pavement sections at Mn/
gradations. A "dense-graded stone," that had been
ROAD. During the testing, a double nomencla-
tested during a cooperative study in Winchendon,
ture was developed for the subgrade samples. Mn/
Massachusetts, was the material in our database
DOT refers to the samples as no. 563, 564, 565,
that most closely matched the size gradation speci-
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