Poor roads and not enough funds to fix them. "Not in my
back yard" responses to requests for new permits for quarries and asphalt
plants. Dwindling supplies of virgin aggregates. Expensive freight costs for
paving remote locations. Environmental concerns. Cracked, rough pavements.

What's the answer for these problems? Cold in-place
recycling. Many agencies, including the Montana Department of Transportation
(MDOT), are using new recycling technology as the solution. On Jan. 1, 2001,
MDOT fully implemented a maintenance program for 5,300 lane miles of secondary
roads. In the past they have found that traditional hot-mix asphalt thin
overlays do little to prevent the recurrence of thermal and reflective
cracking. In 2001, MDOT did one of the first projects using this technology
near Red Lodge and recently completed another project on a 61/2-mile section of
secondary state highway 279 northwest of Helena. The project was chosen as a
trial area to determine if the partial depth cold in-place recycling would reduce
the amount of thermal and reflective cracking and be a cost-effective pavement
maintenance technique.

They thought of it first

Approximately 50% of U.S. rural interstate mileage and
almost 60% of urban interstate mileage is rated in fair to poor condition.
Highway funding just can't keep up in maintaining the current state of our
roads, let alone upgrading those roads and highways to an acceptable condition.
Montana is finding that emulsion cold in-place recycling (CIR) is a
cost-effective solution.

The Federal Highway Administration recently issued a policy
statement, stating, "Recycling and reuse can offer engineering, economic
and environmental benefits. Recycled materials should get first consideration
in materials selection. Determination of the use of recycled materials should
include an initial review of engineering and environmental suitability. An
assessment of economic benefits should follow in the selection
process."

CIR can be used to remove thermal and reflective cracks,
maintain clearances, improve poor aggregate gradations, reuse existing
materials and minimize the need for new materials, as well as strengthen the
pavement.

The innovative process selected by MDOT combines a defined
sampling protocol, an engineered design protocol with performance-related
testing of laboratory prepared samples, quicker field compaction and
construction specifications and a new chemistry (ReFlex) emulsion. Rather than
taking the approach of rejuvenating the existing pavement, this process
identifies the final mixture properties through performance testing.

The new chemistry allows a better coating and higher asphalt
content than conventional CIR. The performance-related specifications include
tests for low-temperature cracking, raveling, strength and stripping
resistance. The specifications also include requirements for the construction
equipment and practices, as well as quality control and quality assurance.

Situated in the mountains and a climate which experiences
temperature extremes, Rte. 279 had severe transverse thermal cracking and the
early signs of intermittent fatigue cracking, but came with a structurally
sound base. Prior to the project, cores were taken from the road following the
defined sampling protocol. These cores were crushed into two gradations (medium
and coarse) and the resultant reclaimed asphalt pavement (RAP) was used for mix
designs in the Koch Pavement Solutions Terre Haute, Ind., laboratory. The
design included formulating an emulsion specifically for the RAP to meet
performance-related specifications for strength and resistance to thermal
cracking, rutting, raveling and moisture damage.

Designs were completed for both the medium and coarse
gradations, so that the design could be matched for the actual gradations
achieved in the field once construction started. The specifications and the
design test results for this project are given in the table above. The design
emulsion content for the medium gradation was 3%, 2.5% for the coarse. Design
water content for both gradations was 2-4%.

Quicker with a kocal

Valentine Surfacing Co., Vancouver, Wash., was the main
contractor for the project, with Century Cos., Lewiston, Mont., as a sub for
the laydown. Prior to construction, the shoulders were bladed back to prevent
their incorporation into the recycled mix.

The project was completed Aug. 1-8, 2003, with little
disruption of traffic (another advantage of in-place recycling). The
temperatures during construction ranged from the mid 80s to the high 90s. In
the partial depth CIR process, 3 in. of the distressed pavement was milled,
leaving sufficient base to support the recycling train. The existing pavement
was milled using a PR-1000 Rotomill, and the millings were processed with an El
Jay Screen Deck and a Cedarapids Hammermill Crusher.

An Eagle Pugmill and an Asphalt Equipment Service Co.
(AESCO) Blending System were used to blend the emulsion with the millings. In
the past, most CIR used the same off-the-shelf emulsions as used for tack coats
and a multitude of other uses. The emulsion used for this project was
engineered specifically to give a chemical break and early strength to the CIR
process, as well as meet the performance specifications.

The ReFlex emulsion was supplied by Koch's Billings, Mont.,
plant. The early strength allows a quicker return to traffic and earlier
placement of a wearing course. According to Chuck Valentine, president of
Valentine Surfacing Co., "The early strength of the ReFlex material is a
very positive aspect. Traffic can get on the recycled mat much earlier (within
1-2 hours) and the potential damage due to traffic is virtually eliminated.
Also, in the states that we CIR, the necessity to reroll is eliminated using
the ReFlex product.

"The key to ReFlex CIR is primarily the laydown and
compaction operation. We have found that the windrow elevator (kocal) is a key
component. The larger, highest-horsepower machine is most desirable because the
mix sets up faster than conventional CIR. Therefore, it is very important to
have a large, high-horsepower kocal to pick the processed material up and
deposit it in the hopper of the paver."

A Lincoln 660 Windrow Elevator fed the recycled mixture into
a Blaw Knox PF 5510 paver which laid the mat. The mat was compacted using two
steel-wheel rollers and one 25-ton rubber-tire roller. Valentine said, "We
have had little difficulty achieving target densities with the ReFlex
product."

The CIR maintained the current profile of the roadway, and
MDOT measurements showed improved rideability. A seal and cover was placed on
the CIR 10 days after the job was completed. Because of a relatively high void
content, a fog seal was considered. However, traffic during the construction
period tightened the mat surface, which allowed the design recommended seal and
cover application rates.

According to Koch technical marketing representative Sean
Pellersels, "Close communication and cooperation between the prime and
subcontractors played a major role in the success of the project, which had a
very smooth mat, high production and limited traffic delays."