Wanted: A Simple Superpave Performance Test
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| States will be able to use the simple Superpave performance test
to tell if their Superpave mix disign can hold up to the traffic and
climate conditions at a project site. |
Implementation of the Superpave mix design system is at an all-time high,
but still missing is a simple test that States can use to tell if their
Superpave mix design will hold up to the traffic and climate conditions
at a project site. Help is on the horizon, however. A team of researchers,
led by Matt Witczak at Arizona State University, is working under a National
Cooperative Highway Research Program contract (NCHRP 9-19) to identify
a simple performance test to be used with the Superpave volumetric mix
design. The team is close to finishing an evaluation of existing tests
of asphalt mixture properties to determine if any can be adapted to be
a simple performance test (see December 1998 Focus).
The test will be pass/fail, indicating whether the mix is acceptable or
not. It will also work in different climates and with various materials,
making it equally applicable in different parts of the country.
Evaluations of various test methods have been completed using materials
from Minnesota's Mn/Road testing facility. Additional evaluations are
underway on the materials from the Federal Highway Administration's (FHWA)
Accelerated Loading Facility at the Turner-Fairbank Highway Research Center
in McLean, Virginia, and the WesTrack pavement testing facility near Reno,
Nevada. The team will recommend the required testing protocols early this
summer.
"It is possible that the team will be recommending a different test
or criteria for rutting than for fatigue," says Katherine Petros
of FHWA. "It is planned that once the protocols have been recommended,
interested State highway agencies will be able to participate in a validation
of the recommended test or tests by using it on some of their mixes of
known performance." For more information, contact Katherine Petros at 415-744-0652 (fax: 415-744-2620; email: katherine.petros@fhwa.dot.gov).
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