10. EMC2 Minnesota RoadFrost heave and freeze -thaw cycling
are problems that damage both paved
and unpaved roads in states as far south
as California, Arizona, New Mexico,
Texas, Arkansas, and North Carolina.
In the northern states and Canada, the
fall and spring frost -heave periods so
weaken highway base materials and subgrade soils that load
limits must be imposed, restricting fully loaded trucks from
these roads on a seasonal basis and slowing the pace of local
commerce. Much of the traditional research of state highway
and transportation departments has been focused on how to
better determine when load limits should be imposed and
when they may be lifted. Attention is now also being focused
on addressing the problems that create the need for these
seasonal load limits: the moisture and frost susceptibility of the
aggregate base course materials and the dynamic movements
in the soil subgrade below them.
Minnesota is noted for its cold climate but Lake of the Woods
County, bordering the Canadian provinces of Manitoba and
Ontario, has double trouble: a high ground water table as
well as cold winter temperatures. The entire county suffers
freeze -thaw weakening of its road bases and subgrades each
year. Roads are, accordingly, subject to seasonal load limits
that are costly to logging and other local businesses who
must cease operations when heavy loads are not permitted
on the roads for months at a time. Pavement damage is
severe even with seasonal load limits in place. Unstabilized
roadbed materials lose their flexural stiffness and their ability
equally problematic. They rut, pothole and erupt in frost
boils during freeze -thaw cycles, and grading is required on a
constant basis. A 1997 statewide survey determined that a
typical aggregate surfaced road in Minnesota is graded every
8.6 days. Constant grading accelerates gravel loss, a problem
which is not only costly but also indicative of a road surface
which is eroding and contributing to the sedimentation of
nearby streams, rivers and lakes.
The County Engineer, an active member of the Local Roads
Research Board of Minnesota, was interested in stabilization
technology that would provide more permanent improvement
for gravel surface roads than the usual calcium chloride
dust palliative treatments applied by Minnesota counties for
summertime dust control. New aggregate surfacing materials
are regularly placed on county roads as part of incremental
construction projects where chip seals and asphalt pavements
are often in the plans at some future time when funding
becomes available. One of the goals of the Local Roads
Research Board was to identify a treatment which could retain
gravel materials and maintain the paving grade over a period
of months or years. With county costs running approximately
$100,000.00 per mile for placement of subbase and aggregate
base course materials, an effective and economical aggregate
treatment would clearly be cost effective.
In the early summer of 1997, the County Engineer decided to
move forward on stabilization of one of his most remote and
high maintenance roads. The road selected, Northwest Angle
Road, which is located out on the end of a wet and wooded
to properly support asphalt pavements. Unpaved roads are peninsula, is in a portion of the United States that is accessible
SOIL STABILIZATION PRODUCTS COMPANY, INC.
Ph: (800)523-9992 or (209)383-3296, Fax: (209)383-7849, Email: info@sspco.com '"
only by driving through Canada, or by boating up the middle
ofLake ofthe Woods through U.S. Waters to reach this isolated
portion of Lake of the Woods County. Northwest Angle Road
was the County Engineer's top priority for stabilization, not
only because of its extremely remote location, but also due
to the high frequency of maintenance grading (two to three
gradings per week) required for this road constructed across
swampy terrain. The deep winter freezes heave the silty soil
subgrades upwards by a foot or more. During spring thaw the
soil becomes so saturated that the entire length of a shovel
handle can be pushed down into the ground with relative
ease.Given these soft subgrade conditions, the unavoidable
seasonal heaving and the poor quality of the locally available
pit run gravel surfacing, Northwest Angle Road presented a
worthy challenge for stabilization technology.
The County Engineer selected a high strength woven
geotextile fabric to help retain the integrity of the gravel
structural section through the periods ofheaving and thawing.
The geotextile fabric was intended to keep the gravel layer
intact and stop the eruptions of subgrade soils up through
the gravel in a spring thaw phenomenon known as "frost
boil." The county had previous experience with light weight
geotextile fabrics and had found that they ripped apart during
the dramatic seasonal ground movements. So, a high strength
woven geotextile was installed as an underlayment for the
new pit run gravel surfacing that was placed along Northwest
Angle Road.
Even with the geotextile underneath, it was clear the gravel
surfacing would still be affected by frost -heave and rainfall,
resulting in ruts and potholes that required constant
maintenance. To solve this problem, the EMC SQUARED®
Stabilizer was selected for the project. This product
technology, a concentrated liquid stabilizer (CLS) treatment
from Soil Stabilization Products Company, Inc. (SSPCo), was
proven in cold climate applications and was effective with
many non -plastic (non -cohesive) aggregates and recycled
pavement materials as well as with cohesive aggregates and
clayey soils. Six miles of the newly placed gravel surfacing
was treated with the EMC SQUARED Stabilizer to a three
inch depth by the county road maintenance crew. The liquid
stabilizer solution was blade mixed with the gravel during
application. The treated gravel mixture was then graded
to shape and compacted with a steel drum vibratory roller.
The county crew was working on their first stabilization
project, and they perfected their technique for shaping of
the running surface and timing their compaction operations
as the stabilizer application progressed down the road. The
cohesive forces added by the stabilizer treatment were obvious,
and they commented that the treated gravel mixture got very
"heavy" to process and shape with the motor grader as they
prepared the surfacing for compaction. The County Engineer
commented that the stabilized aggregate set up just like
concrete once the compaction and final grading work was
completed. Within several weeks of construction, the crew
applied a calcium chloride dust control treatment on top of
the stabilized running surface.
The reconstructed Northwest Angle Road has now been
in service for over thirteen years, servicing an average daily
traffic count of approximately 140 cars and trucks. The county
applies calcium chloride treatment to the road surface each
summer for dust control and to help retain the fine -sized
aggregate materials on top of the stabilized gravel running
surface. Bruce Hasbargen, the County Engineer monitoring
the project from 1999 through 2010, reports that as of year
2010 the six mile section treated with the EMC SQUARED
Stabilizer remains in excellent condition. Considering the
poor quality pit run aggregate, a nonplastic material with just
4.5 % #200 fines content, the near proximity of ground water,
the extreme cold climate, and service as a running surface
for logging truck and vehicular traffic without protection by
asphalt pavement or bituminous surface treatment, the EMC
SQUARED product technology has proven effective under
what are truly "worst case" field testing conditions.
To learn more about Soil Stabilization Products Company and the EMC SQUARED System visit
www.sspco.com
SOIL STABILIZATION PRODUCTS COMPANY, INC.
Ph: (800)523-9992 or (209)383-3296, Fax: (209)383-7849, Email: info@sspco.com