Comparison of Moduli of Kansas
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Date
2010Author
Gedafa, Daba S.
Hossain, Mustaque
Romanoschi, Stefan
Gisi, Andrew J.
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Show full item recordAbstract
Currently, hot-mix asphalt (HMA) mixture design and pavement structural
design are not fully integrated, although Superpave® asphalt mixture
design is somewhat project specific. The objective of this study was to
compare elastic moduli assumed during structural design of pavements
with the backcalculated moduli of HMA layers obtained from the falling
weight deflectometer (FWD) tests and the dynamic modulus values measured
in the laboratory. Five newly built Superpave pavements, designed
by using the 1993 AASHTO Design Guide, were selected as study sites in
this research. Deflection data were collected with a Dynatest 8000 FWD
on a 1,000-ft test section at each site. The HMA layer moduli were then
backcalculated by using an elastic-layer analysis program. Full depth cores
were taken from each section and tested in the laboratory for dynamic
moduli. The results showed that backcalculated and laboratory moduli
were somewhat comparable for all practical purposes. The laboratory
dynamic moduli increased with the loading frequency, indicating the
need for consideration of vehicle speeds in the HMA pavement structural
design. HMA design moduli, assumed by the Kansas Department of
Transportation during pavement structural design, are lower than both
backcalculated and laboratory dynamic moduli. Thus, current HMA
design moduli are achievable in the field through Superpave mixture
design, despite the fact that the pavement structural design and mix design
processes are not integrated.