University of Minnesota researchers have released a report on
dynamic and resilient modulus testing of four standard Mn/DOT asphalt
mixtures. Engineers hope that research of this kind will make complex
modulus a standard design parameter in the mechanistic pavement
design process, and lead to the ability to predict rutting and fatigue
cracking in paved surfaces.
Dynamic and Resilient Modulus of Mn/DOT Asphalt Mixtures, by Mihai
Marasteanu, Timothy Clyne, Xinjun
Li, and Eugene Skok of the Department
of Civil Engineering, covers tests carried out on pavement samples
from the Mn/ROAD testing facility.
Their work was prompted by recommendations in the 2002 Guide for
the Design of New and Rehabilitated Pavement Structures, currently
under development by the National Cooperative Highway Research Program,
that dynamic modulus serve as a design parameter and a simple performance
test. The team used procedures specified in the 2002 Design Guide
to test samples of four typical Minnesota pavement mixes at a variety
of temperatures and frequencies.
The researchers' main objective generate master curves of modulus
vs. frequency from the test data. They then compared the experimental
master curves to modulus values obtained from two predictive equations
proposed by 2002 Design Guide.
In two of the four cases, the researchers were able to obtain
experimental modulus curves that corresponded well to the predicted
values. However, their results indicated that sample preparation
procedures have a significant impact on the results, so adherence
to the Design Guide specifications is essential. In the other two
cases, experimental results did not conform well to the predicted
values, indicating a need for additional research.
The report (Mn/DOT 2003-09) is available from the Minnesota Department
of Transportation's Research Services Section Web site at www.research.dot.state.mn.us or from the Minnesota Local Road Research Board (LRRB) Web site
at www.lrrb.gen.mn.us/PDF/200309.pdf. |
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Friday, 20 July 2007