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Onsite Use of Recycled Asphalt Pavement Materials and Geocells to ...

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Depth (cm.)<br />

10<br />

14<br />

18<br />

22<br />

26<br />

Before test<br />

AfterTest<br />

30<br />

-100 -80 -60 -40 -20 0 20 40 60 80 100<br />

Figure 4.11 Pr<strong>of</strong>iles <strong>of</strong> the HMA surface before <strong>and</strong> after the test for the 15 cm thick<br />

unreinforced RAP base section<br />

The permanent deformation was obtained after unloading <strong>of</strong> each cycle. Figure 4.12<br />

presents the measured permanent deformations <strong>of</strong> the pavement at the surface, at the <strong>to</strong>p <strong>of</strong> the<br />

base, <strong>and</strong> at the <strong>to</strong>p <strong>of</strong> the subgrade. The difference in the permanent deformations between the<br />

HMA surface <strong>and</strong> the base is the compression <strong>of</strong> the HMA surface while that between the base<br />

<strong>and</strong> the subgrade is the compression <strong>of</strong> the base course. At the end <strong>of</strong> the test, the permanent<br />

deformation <strong>of</strong> the subgrade was approximately 50% <strong>of</strong> the <strong>to</strong>tal permanent deformation. The<br />

surface deformations at different distances from the center were obtained by the displacement<br />

transducers while the deformations at the <strong>to</strong>p <strong>of</strong> the base <strong>and</strong> subgrade were obtained by the tell-<br />

tales. It is shown that the surface permanent deformation was higher at the center <strong>and</strong> decreased<br />

at the distances <strong>of</strong> 25, <strong>and</strong> 50 cm away from the center. The elastic deformation (i.e., the rebound<br />

during the unloading <strong>of</strong> each cycle) as shown in figure 4.13 increased up <strong>to</strong> 40 cycles <strong>of</strong> loading<br />

<strong>and</strong> then decreased slightly at a small rate until the end <strong>of</strong> the test. The elastic deformation was<br />

much smaller than the permanent deformation <strong>and</strong> was less than 10% <strong>of</strong> the permanent<br />

deformation at the end <strong>of</strong> the test.<br />

Distance from center (cm.)<br />

57

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