Aggregate Tests for Hot-Mix Asphalt Mixtures Used in Pavements (2006) / Chapter Skim
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Pages 24-33
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From page 24... ...
For the current study, a correlation matrix was developed for eight of the coarse aggregate tests and three rutting parameters. The total rut depth at 20,000 wheel passes was not included because the CA-3 (Uncrushed Gravel)
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From page 25... ...
To determine sensitivity of coarse aggregate UVA to traffic levels, the effect of coarse aggregate UVA on the number of APT wheel passes to reach total rut depths of 3.5 and 7.0 mm was examined; results are shown in Figures 19 and 20, respectively. The 7.0-mm total rut depth was selected because it was the minimum total rut depth exhibited at 20,000 wheel passes during the APT tests; the 3.5-mm total rut was arbitrarily chosen as one-half of the 7.0-mm rut depth.
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From page 26... ...
Rutting parameters used to evaluate fine-graded HMA mixtures' rutting potential were rut depths at 1,000; 5,000; and 20,000 APT wheel passes, and early and late traffic rutting rates. Correlation analyses were conducted between the rutting parameters and the fine aggregate test results.
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From page 27... ...
The response variables were rut depths at 1,000; 5,000; and 20,000 APT wheel passes; and early and late traffic rutting rates. y = -0.73x + 44.44 R2 = 0.28 0 5 10 15 20 40 42 44 46 48 50 UVA, % To ta l R ut D ep th @ 5 00 0 W he el P as se s, m m y = -1.03x + 60.32 R2 = 0.46 0 5 10 15 20 25 30 35 40 42 44 46 48 50 UVA, % To ta l R ut D ep th @ 2 00 00 W he el Pa ss es , m m Figure 23.
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From page 28... ...
Furthermore, at UVA values of around 39 to 40 percent, HMA mixtures tested in both the GLWT and APT exhibited significant increases in rut depths. Based on results in this research and those reported by Kandhal and Parker, it appears that fine aggregate UVA is a good predictor variable of HMA rutting performance.
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From page 29... ...
Sensitivity of the fine aggregate UVA to APT traffic levels was analyzed at the 7.5-mm and 10-mm total rut depths. Figures 27 and 28 show the relationships between fine aggregate UVA and the number of APT wheel passes required to reach a 7.5- and 10-mm total rut depth, respectively.
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From page 30... ...
Parameters evaluated included rut depths at 1,000 and 5,000 APT wheel passes and 30 rutting rates for both early and late traffic. The results are shown in Table 24.
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From page 31... ...
Again, 9 mm was chosen because it is the maximum amount of rutting experienced. Figures 35 and 36 show relationships between fine aggregate UVA and the number of APT wheel passes in the presence of moisture required to reach 4.5- and 9-mm total rut depths, respectively.
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From page 32... ...
Again, at the lower rut depth, the change in fine aggregate UVA makes very little difference in the number of APT wheel passes; however, at the 9-mm rut depth, slight changes in the fine aggregate UVA appear to make a very large difference in the number of wheel passes. Figure 37 presents the APT rut depths as a function of the number of wheel passes for each of the fine aggregates used in the moisture susceptibility portion of the study.
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From page 33... ...
as a function of the coarse aggregate UVA and FOE21, shown in Figures 38 and 39, respectively, indicates a trend in the data. As UVA or FOE21 increase, so do the number of APT wheel passes required to fatigue HMA mixtures.
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