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What is Superpave?
"Superpave" is an overarching term for the results of the asphalt research
portion of the 1987 - 1993 Strategic Highway Research Program (SHRP).
Superpave consists of (1) an asphalt binder specification, (2) an
HMA mix design
method and (3) HMA tests and performance prediction models. Each one of
these components is referred to by the term "Superpave". This section
provides a brief overview and background of Superpave.
In 1987 the U.S. Congress established a 5-year, $150 million applied research
program aimed at improving the performance, durability, safety, and efficiency
of the Nation’s highway system. Called the Strategic Highway Research
Program (SHRP), this program was officially authorized by the Surface
Transportation and Uniform Relocation Act of 1987 and consisted of research
concentrated in four key areas (FHWA, 1998):
- Asphalt. This area consists of research to develop a
completely new approach to HMA mix design.
- Concrete and structures. This area consists of research in
the areas of mix design and assessing, protecting and rehabilitating concrete
pavements and structures.
- Highway operations. This area consists of pavement
preservation, work zone safety and snow and ice control research.
- Pavement performance. This area consists of the
Long
Term Pavement Performance Program (LTPP), a 20-year study of
over 2,000 test sections of in-service U.S. and Canadian pavements to improve
guidelines for building and maintaining pavements.
SHRP research activities were completed in 1992 and SHRP was closed down in
1993. To date, SHRP has produced more than 100 new devices, tests and
specifications and, perhaps more importantly, has spawned a full-scale on-going
implementation drive by such organizations as the FHWA, AASHTO and TRB.
The SHRP asphalt research program, the largest SHRP program at $53 million
(FHWA, 1998), had three primary objectives (NECEPT, 2001):
- Investigate why some pavements perform well, while others do not.
- Develop tests and specifications for materials that will out-perform and
outlast the pavements being constructed today.
- Work with highway agencies and industry to have the new specifications put
to use.
The final product of this research program is a new system referred to as
"Superpave", which stands for SUperior PERforming Asphalt PAVEments.
Superpave, in its final form consists of three basic components:
- An asphalt binder specification. This is the
PG asphalt binder
specification.
- A design and analysis system based on the volumetric properties of the
asphalt mix. This is the Superpave mix design
method.
- Mix analysis tests and performance prediction models. This
area is not yet complete. Test development and evaluation is on-going as
of 2002.
Each one of these components required new specifications and performance
standards as well as new testing methods and devices.
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