Asphalt Pavement Magazine - May/June 2018 - 37

Recycled Tire Rubber Mixture Yields High-Performing Road
cracking performance in the
laboratory of both mixtures.
The Asphalt Pavement Analyzer,
Hamburg Wheel Tracking Test, and
Flow Number were all used to assess
the rutting susceptibility of these
mixtures. In every case, the rubbermodified mixture had equivalent
or better performance than the
polymer-modified mixture.
The Energy Ratio developed by the
University of Florida and the semicircular bend (SCB) test developed
by the Louisiana Transportation
Research Center (LTRC) were used
to evaluate the potential for surface
cracking in the mixtures. The energy
ratio (ER) test uses two parameters
to determine if the mixture is brittle
(DSCEHMA < 0.75) or susceptible to
surface cracking (ER < 1.95). Both of
the mixtures more than tripled the
minimum DSCEHMA requirement
and doubled the minimum ER. The
rubber-modified mixture had a
slightly higher ER. For the SCB test,
the J-Integral is used to determine
cracking susceptibility. The higher
the J-integral, the less susceptible
the mixture should be to cracking.
The J-integral for the rubber mixture
was 31 percent greater than that
of the polymer-modified mixture,
suggesting greater resistance to
surface cracking.
While laboratory testing can
be used to evaluate and predict
mixture performance in the field,
the ultimate proof of a technology's
appropriateness is field performance.
The field performance of each test
section was evaluated to assess
rutting, cracking, texture, and
smoothness. The rut depths, texture,
and smoothness of each test section
were evaluated using an inertial
profiler while cracking was assessed
by monitoring three 100-foot test
strips on each test section.
After seven years of trafficking,
both test sections are free of
cracking and major rutting (<4 mm
in each section). Additionally, both
test sections were built smooth (IRI
< 45 in./mile), and there has been

no deterioration in the pavement
smoothness over time. No change
in texture has occurred either. Since
the RTR-modified mixture has
performed in the lab and the field
over seven years, data are available
which show RTR-mixtures can be
used as well as provide agencies and
the riding public with a smooth
wearing surface that will perform
well over time. AP

898411_TransTech.indd 1

Writer bio: Dr. J. Richard Willis is the
Director of Pavement Engineering and
Innovation for NAPA. He can be reached
at RWillis@AsphaltPavement.org.
Editor's Note: Parts of this article
originally appeared in the Spring
2016 issue of Asphalt Technology News,
and were re-printed with permission
from the National Center for
Asphalt Technology.

Asphalt Pavement Magazine - May/June 23/02/18
2018 * 37
11:46 PM


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Asphalt Pavement Magazine - May/June 2018

Table of Contents for the Digital Edition of Asphalt Pavement Magazine - May/June 2018

Chairman’s Commentary
Industry News
Tools for the Trade
A Green Answer for Higher Recycling
Reducing Rolling Resistance to Reduce Emissions
Recycled Tire Rubber Mixture Yields High-Performing Road
The Pavement Economics Committee: A Powerful Partnership
Focus on the Field: Job Spotlight
Industry Events
Index of Advertisers/Advertisers.com
Perspectives
Asphalt Pavement Magazine - May/June 2018 - intro
Asphalt Pavement Magazine - May/June 2018 - cover1
Asphalt Pavement Magazine - May/June 2018 - cover2
Asphalt Pavement Magazine - May/June 2018 - 3
Asphalt Pavement Magazine - May/June 2018 - 4
Asphalt Pavement Magazine - May/June 2018 - 5
Asphalt Pavement Magazine - May/June 2018 - 6
Asphalt Pavement Magazine - May/June 2018 - 7
Asphalt Pavement Magazine - May/June 2018 - 8
Asphalt Pavement Magazine - May/June 2018 - Chairman’s Commentary
Asphalt Pavement Magazine - May/June 2018 - 10
Asphalt Pavement Magazine - May/June 2018 - Industry News
Asphalt Pavement Magazine - May/June 2018 - 12
Asphalt Pavement Magazine - May/June 2018 - 13
Asphalt Pavement Magazine - May/June 2018 - 14
Asphalt Pavement Magazine - May/June 2018 - 15
Asphalt Pavement Magazine - May/June 2018 - 16
Asphalt Pavement Magazine - May/June 2018 - 17
Asphalt Pavement Magazine - May/June 2018 - Tools for the Trade
Asphalt Pavement Magazine - May/June 2018 - 19
Asphalt Pavement Magazine - May/June 2018 - 20
Asphalt Pavement Magazine - May/June 2018 - 21
Asphalt Pavement Magazine - May/June 2018 - A Green Answer for Higher Recycling
Asphalt Pavement Magazine - May/June 2018 - 23
Asphalt Pavement Magazine - May/June 2018 - 24
Asphalt Pavement Magazine - May/June 2018 - 25
Asphalt Pavement Magazine - May/June 2018 - 26
Asphalt Pavement Magazine - May/June 2018 - 27
Asphalt Pavement Magazine - May/June 2018 - Reducing Rolling Resistance to Reduce Emissions
Asphalt Pavement Magazine - May/June 2018 - 29
Asphalt Pavement Magazine - May/June 2018 - 30
Asphalt Pavement Magazine - May/June 2018 - 31
Asphalt Pavement Magazine - May/June 2018 - Recycled Tire Rubber Mixture Yields High-Performing Road
Asphalt Pavement Magazine - May/June 2018 - 33
Asphalt Pavement Magazine - May/June 2018 - 34
Asphalt Pavement Magazine - May/June 2018 - 35
Asphalt Pavement Magazine - May/June 2018 - 36
Asphalt Pavement Magazine - May/June 2018 - 37
Asphalt Pavement Magazine - May/June 2018 - 38
Asphalt Pavement Magazine - May/June 2018 - 39
Asphalt Pavement Magazine - May/June 2018 - The Pavement Economics Committee: A Powerful Partnership
Asphalt Pavement Magazine - May/June 2018 - 41
Asphalt Pavement Magazine - May/June 2018 - 42
Asphalt Pavement Magazine - May/June 2018 - 43
Asphalt Pavement Magazine - May/June 2018 - 44
Asphalt Pavement Magazine - May/June 2018 - 45
Asphalt Pavement Magazine - May/June 2018 - 46
Asphalt Pavement Magazine - May/June 2018 - 47
Asphalt Pavement Magazine - May/June 2018 - Focus on the Field: Job Spotlight
Asphalt Pavement Magazine - May/June 2018 - 49
Asphalt Pavement Magazine - May/June 2018 - 50
Asphalt Pavement Magazine - May/June 2018 - 51
Asphalt Pavement Magazine - May/June 2018 - Industry Events
Asphalt Pavement Magazine - May/June 2018 - 53
Asphalt Pavement Magazine - May/June 2018 - 54
Asphalt Pavement Magazine - May/June 2018 - Index of Advertisers/Advertisers.com
Asphalt Pavement Magazine - May/June 2018 - 56
Asphalt Pavement Magazine - May/June 2018 - 57
Asphalt Pavement Magazine - May/June 2018 - Perspectives
Asphalt Pavement Magazine - May/June 2018 - cover3
Asphalt Pavement Magazine - May/June 2018 - cover4
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