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Distress
Identification
Existing pavement condition - quantifying the condition of
the existing roadway will provide an increased understanding
of past performance. Knowing when and how a pavement
distresses will inform the pavement designer of
potentials for underlying base or subgrade problems,
inadequate structure, insufficient material properties,
increased truck loading, etc.
Flexible Pavements
(download EverSeries software)
WSDOT has developed, in conjunction with the University of
Washington, a mechanistic-empirical overlay design
procedure. This procedure incorporates the use of
pavement deflections measured using a Falling
Weight Deflectometer, layered elastic theory (stress and
strains), seasonal variations in the base and subgrade
materials due to temperature, and truck loading (ESAL) to
determine overlay thickness. |
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Evercalf - Backcalculation Program
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Everpave - Mechanistic-Empirical Asphalt Concrete
Overlay Design Procedure
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Rigid
Pavements
Concrete pavements in Washington State have typically
out-performed the expected design periods. The
concrete pavements constructed in the 1960's - 1970's were
designed for a 20-year service life. Not only have
these pavements reached ages of 30 to 40 years, but they
have also carried anywhere from two to five times their
design traffic loads. |
This exceptional
performance, in large part, is due to good design and
extremely hard aggregate. However, those concrete
pavements are now in need of rehabilitation with high levels
of joint faulting. Faulting is a step difference in
adjoining concrete slabs.
For years, the only agreed upon
rehabilitation was a thick asphalt concrete overlay. |
Concrete Joint Faulting |
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of these overlays was satisfactory for a number of years
until reflective cracking began to decrease the service life
of the pavement. Currently, WSDOT is actively pursuing
the use of load transfer restoration and diamond grinding to
extend the life of concrete pavements. As future
rehabilitation options develop, WSDOT will fully investigate
and implement viable options as necessary.
In 1997, WSDOT received delivery of a three-dimensional
finite element program that will significantly enhance the
ability to investigate concrete performance and
rehabilitation alternatives. The following
illustrations show the main screen for the EverFE computer
program and an example of the program results. This
program is currently being modified and should be available
Fall 2001.
EverFE
EverFE Results
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