Field Verification of Proposed Changes to the AASHTO R 30 Procedures for Laboratory Conditioning of Asphalt Mixtures (2019) / Chapter Skim
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From page 14... ...
14 Findings and Applications Chapter 3 presents the data collected from the eight field sites in which periodic post-construction coring was allowed. The analysis of long-term aging is presented in two ways.
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15 y = 74.191x0.218 R² = 0.3968 0 200 400 600 800 1000 1200 1400 1600 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 M R S ti ff ne ss ( ks i) Cumulative Degree-Days (°F-days)
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16 y = 147.44x0.1795 R² = 0.8006 0 200 400 600 800 1000 1200 1400 1600 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 M R S ti ff ne ss ( ks i) Cumulative Degree-Days (°F-days)
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17 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0 30000 60000 90000 120000 M R S tif fn es s R at io Cumulative Degree-Days (°F-days) Predicted MeasuredR2 = 0.51 Figure 12.
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18 finding is sensible because the uncertainty of predictions tends to increase further in the future. The data in Table 3 suggest that a more realistic approach to LTOA could be aging loose mix at 185°F (85°C)
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19 with high-absorptive aggregates and low-absorptive aggregates at the Iowa field site had similar MR stiffness values, so the points were close to the line of equality. The mixture with a low-absorption aggregate at the Florida field site exhibited higher MR stiffness values, which is most likely a function of the RAP content in the mixture.
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20 Figure 19 shows the plot of MR stiffness values for mixtures with Binder A versus those for mixtures with Binder V The mixture with Binder A has much higher MR stiffness values, which means the factor of asphalt source is significant based on MR stiffness testing.
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21 asphalts at the time of construction showed very little difference between them. The only indication was that the intermediate PG grade for Binder V was about 3°C lower than that for Binder A
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22 y = 1.3152x 0 200 400 600 800 1000 1200 1400 1600 1800 0 200 400 600 800 1000 1200 1400 1600 1800 R A P/ R A S M R S tif fn es s ( ks i) No RAP/RAS MR Stiffness (ksi)
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23 an effect on stiffness of HMA. It may be that the presence of WMA technology, whether foaming or additives, created the difference between HMA and WMA.
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24 0 200 400 600 800 1000 1200 1400 1600 0 20000 40000 60000 80000 100000 M R S ti ff ne ss (k si ) Cumulative Degree-Days (°F-days)
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25 0 200 400 600 800 1000 1200 1400 1600 0 20000 40000 60000 80000 100000 M R S ti ff ne ss (k si ) Cumulative Degree-Days (°F-days)
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26 y = 0.9897x 0 100 200 300 400 500 600 0 100 200 300 400 500 600 H ig h T em pe ra tu re M R S ti ff ne ss ( ks i) Control Temperature MR Stiffness (ksi)
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From page 27... ...
27 between stiffness and temperature-time are best modeled for warm and cold climates separately using a power curve. To compare laboratory LTOA protocols to field aging, a property ratio (MR stiffness ratio)
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28 Field Site Months after Placement CDD AV, % MR stiffness (ksi) CT Index Texas I 60 89,777 7.7 1,433 3 New Mexico 22 29,158 4.5 1,080 27 Wyoming 59 49,490 3.6 370 52 South Dakota 57 47,785 6.4 350 37 Iowa 10 6,174 N/A 231 249 Florida 44 66,638 5.7 1,073 41 51 78,565 5.8 1,128 30 Indiana 47 44,065 8.0 1,086 76 Table 7.
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From page 29... ...
29 Figure 37. HMA CT index versus CDD global plot (all locations)
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