Asphalt Pavement Magazine - September/October 2016 - 30


Visitors to NCAT walk the pavement test sections and see first-hand the diverse test results.

U.S. Route 280 near Opelika,
Ala. Thirty-four treatments and
treatment combinations were
applied, including crack sealing,
microsurfacing, chip seals, fog
seals, scrub seals, cape seals, thin
asphalt overlays, and cold recycling
(both in-place and central-plant
production). The U.S. 280 sections
will help quantify preservation
benefits for typical highway
traffic levels, in between that of
the Test Track and Lee Road 159.
Many of the same preservation
treatments will also be placed
on comparable roadways in
Minnesota this year through the
MnROAD partnership, addressing
the needs of both northern and
southern climates through one
collaborative experiment.
The second focus of the
MnROAD/NCAT partnership is
validating laboratory cracking tests
by correlating lab results with field
performance. Durability has always
been a concern and is even more
so now, as higher recycled binder
percentages tend to reduce strain
tolerance. Because traditional mix
criteria have weak relationships to
performance, a reliable cracking
test is needed to eliminate mixes
that are not durable before they
are placed on a roadway. The
ultimate goal is a cracking test that
relates well to field performance,
is practical for use in mix design

verification and quality control
testing, and can accommodate
recycled materials, new and future
additives, and mix combinations.
A number of laboratory cracking
tests are being evaluated, including
the semi-circular bend test (both
Illinois and Louisiana methods),
the energy ratio method, and the
Texas overlay test. The MnROAD/
NCAT experiments will also provide
data that will help set specification
criteria for cracking tests.
Seven sections were constructed
at the Test Track in 2015 with a
variety of surface mixes expected to
have a range of top-down cracking.
Other factors affecting cracking
potential, including underlying
pavement structure and aging
differences, were controlled to
the fullest extent possible. The
control section with 20 percent
RAP and PG 67-22 has medium
expected cracking potential, as
well as the 35 percent RAP section
with a softer binder (PG 58-28).
Two sections have high cracking
potential: the control mix with
0.5 percent lower asphalt content
and low density (approximately
90 percent) and the control mix
with 5 percent RAS. Three sections
are expected to have low cracking
potential: the control mix with high
density (approximately 96 percent),
the control mix with highly
polymer-modified asphalt, and the

30 * View past issues online at www.naylornetwork.com/nap-nxt

Arizona gap-graded GTR mix with
15 percent RAP.
Eight sections will be constructed
this fall on the MnROAD mainline
to investigate primarily lowtemperature cracking. Mixes will
include different binder grades
and different percentages of RAP
and RAS. One mix will feature
highly polymer-modified asphalt.
For low-temperature cracking,
laboratory testing of the MnROAD
mixes will include the disk-shaped
compact tension (DCT) test and
the semi-circular bend test (Illinois
and Minnesota methods). The test
sections may also experience topdown and/or fatigue cracking, so
plant mix will also be evaluated
using the overlay test and bending
beam fatigue test.
Results from the pavement
preservation and cracking
experiments will be presented at the
next Test Track Conference, March
27-29, 2018, in Auburn, Ala. Going
forward, NCAT plans to continue
evaluating innovative pavement
technologies such as rejuvenators,
cold recycling, and high modulus
mixes. The Group Experiment
concept will likely continue, perhaps
with validating mix performance
tests and calibrating mechanisticempirical design models,
particularly for non-traditional
materials. Future research might
include evaluating heavier loads
on pavements or exploring optimal
ways to develop tire-pavement
friction. Regardless of the research
needed, facilities such as the NCAT
Test Track and MnROAD can help
ensure that innovative pavement
technologies are safe and durable.
There is also opportunity for
construction of a similar facility
in the western states. Continued
innovation through pavement
research is a vital part of costeffectively maintaining our highway
infrastructure. The future health of
our nation depends on it. AP
Courtney Jones is a freelance writer
who works frequently with NCAT. She
resides in Headland, Ala.


http://www.naylornetwork.com/nap-nxt

Table of Contents for the Digital Edition of Asphalt Pavement Magazine - September/October 2016

Chairman’s Commentary
Industry News
Innovation in Mindset and Technology
Innovative Pavement Research
Freight Innovations in Our Future
Creating a Sustainability Program:
Industry Calendar
Index of Advertisers / Advertisers.com
Asphalt Pavement Magazine - September/October 2016 - Cover1
Asphalt Pavement Magazine - September/October 2016 - IBD_L
Asphalt Pavement Magazine - September/October 2016 - IBD
Asphalt Pavement Magazine - September/October 2016 - cover2
Asphalt Pavement Magazine - September/October 2016 - 3
Asphalt Pavement Magazine - September/October 2016 - 4
Asphalt Pavement Magazine - September/October 2016 - 5
Asphalt Pavement Magazine - September/October 2016 - 6
Asphalt Pavement Magazine - September/October 2016 - 7
Asphalt Pavement Magazine - September/October 2016 - 8
Asphalt Pavement Magazine - September/October 2016 - Chairman’s Commentary
Asphalt Pavement Magazine - September/October 2016 - 10
Asphalt Pavement Magazine - September/October 2016 - 11
Asphalt Pavement Magazine - September/October 2016 - 12
Asphalt Pavement Magazine - September/October 2016 - Industry News
Asphalt Pavement Magazine - September/October 2016 - 14
Asphalt Pavement Magazine - September/October 2016 - 15
Asphalt Pavement Magazine - September/October 2016 - 16
Asphalt Pavement Magazine - September/October 2016 - 17
Asphalt Pavement Magazine - September/October 2016 - 18
Asphalt Pavement Magazine - September/October 2016 - Innovation in Mindset and Technology
Asphalt Pavement Magazine - September/October 2016 - 20
Asphalt Pavement Magazine - September/October 2016 - 21
Asphalt Pavement Magazine - September/October 2016 - 22
Asphalt Pavement Magazine - September/October 2016 - 23
Asphalt Pavement Magazine - September/October 2016 - 24
Asphalt Pavement Magazine - September/October 2016 - 25
Asphalt Pavement Magazine - September/October 2016 - 26
Asphalt Pavement Magazine - September/October 2016 - Innovative Pavement Research
Asphalt Pavement Magazine - September/October 2016 - 28
Asphalt Pavement Magazine - September/October 2016 - 29
Asphalt Pavement Magazine - September/October 2016 - 30
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Asphalt Pavement Magazine - September/October 2016 - 31
Asphalt Pavement Magazine - September/October 2016 - 32
Asphalt Pavement Magazine - September/October 2016 - Freight Innovations in Our Future
Asphalt Pavement Magazine - September/October 2016 - 34
Asphalt Pavement Magazine - September/October 2016 - 35
Asphalt Pavement Magazine - September/October 2016 - 36
Asphalt Pavement Magazine - September/October 2016 - Creating a Sustainability Program:
Asphalt Pavement Magazine - September/October 2016 - 38
Asphalt Pavement Magazine - September/October 2016 - 39
Asphalt Pavement Magazine - September/October 2016 - 40
Asphalt Pavement Magazine - September/October 2016 - 41
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Asphalt Pavement Magazine - September/October 2016 - 46
Asphalt Pavement Magazine - September/October 2016 - 47
Asphalt Pavement Magazine - September/October 2016 - 48
Asphalt Pavement Magazine - September/October 2016 - Industry Calendar
Asphalt Pavement Magazine - September/October 2016 - 50
Asphalt Pavement Magazine - September/October 2016 - Index of Advertisers / Advertisers.com
Asphalt Pavement Magazine - September/October 2016 - 52
Asphalt Pavement Magazine - September/October 2016 - 53
Asphalt Pavement Magazine - September/October 2016 - 54
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Asphalt Pavement Magazine - September/October 2016 - 58
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