Currently, MnDOT pavement design recommends granular equivalency, GE = 1.0 for non-stabilized full-depth
reclamation (FDR) material, which is equivalent to class 5 material. For stabilized full-depth reclamation (SFDR),
there was no guideline for GE at the time this project was initiated (2009). Some local engineers believe that GE of
FDR material should be greater than 1.0 (Class 5), especially for SFDR. In addition, very little information is
available on seasonal effects on FDR base, especially on SFDR base. Because it is known from laboratory studies
that SFDR contains less moisture and has higher stiffness (modulus) than aggregate base, it is assumed that SFDR
should be less susceptible to springtime thawing.
Falling Weight Deflectometer (FWD) tests were performed on seven selected test sections on county roads in
Minnesota over a period of three years. During spring thaw of each year, FWD testing was conducted daily during
the first week of thawing in an attempt to capture spring thaw weakening of the aggregate base. After the spring
thaw period, FWD testing was conducted monthly to study base recovery and stiffness changes through the
GE of SFDR was estimated using a method established by MnDOT using FWD deflections, and the GE of SFDR is
about 1.5. The value varies from project to project as construction and material varies from project to project. All
the materials tested showed seasonal effects on stiffness. In general, the stiffness is weaker in spring than that in
summer and fall.
Department of Civil Engineering, University of Minnesota; Minnesota Department of Transportation
Tang, Shuling; Cao, Yuejian; Labuz, Joseph F..
Structural Evaluation of Asphalt Pavements with Full-Depth Reclaimed Base.
Minnesota Department of Transportation.
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