New Asphalt
Temperature Prediction Standard Adopted
A new
asphalt pavement temperature prediction standard developed through
the Long-Term Pavement Performance (LTPP) program has been adopted
by the American Association of State Highway and Transportation Officials
(AASHTO) Subcommittee on Materials. The standard provides an improved
method for predicting the temperature within the asphalt layers of
a pavement, using readily available data such as the infrared pavement
surface temperature collected during routine deflection testing, the
average air temperature the day before testing, and the time of testing.
Being
able to accurately predict the pavement temperature and its effect
on the deflection testing is important, as deflection testing is used
to evaluate such pavement characteristics as axle or vehicle load
capacity, structural life, and uniformity. To effectively analyze
the data collected, the deflection results must be adjusted to account
for both seasonal and temperature variations. Along with the temperature
prediction method, the LTPP program has developed procedures for adjusting
the deflection data for temperature. Applying these procedures allows
data collected under varying temperature conditions to be compared
and used interchangeably.
The new
AASHTO standard, entitled Prediction of Asphalt-Bound Pavement Layer
Temperatures (No. T317-02), will be published in the 22nd edition
of AASHTO's Standard Specifications for Transportation Materials and
Methods of Sampling and Testing. The new edition is due out in August
2002. For more information, contact the AASHTO Publications Order
Department at 1-800-231-3475 (Web: www.transportation.org/publications/bookstore.nsf).
The temperature prediction and data adjustment procedures developed
by the LTPP program can be found in the report, Temperature Predictions
and Adjustment Factors for Asphalt Pavements (Publication No. FHWA-RD-98-085).
The report is available on the LTPP Web site at http://www.fhwa.dot.gov/pavement/pub_listing.cfm?areas=LTPP.
It can also be obtained from the Federal Highway Administration (FHWA)
Research and Technology Report Center at 301-577-0818 (fax: 301-577-1421).
For more
information, contact Cheryl Richter at FHWA, 202-493-3148 (email:cheryl.richter@fhwa.dot.gov).
