The National Academies Press

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Pages 14-28

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From page 14... ... 14 Research Approach Overview The CAI, which is used to relate the pavement temperature history to the required laboratory aging duration, was recalibrated and simplified using original binders, aggregates, and field cores from selected pavement sections. Emphasis now was placed on other mixture types, i.e., WMA mixtures, mixtures containing RAP, and PMA mixtures, which were not considered thoroughly in the initial calibration of the laboratory aging procedure. Read the entire page →
From page 15... ... Refinement of the Climate-Based, Predefined Laboratory Aging Durations 15 and the number of cores tested are noted in the table, along with check marks to indicate that the core contained a modern mixture (WMA, RAP, or PMA) Read the entire page →
From page 16... ... Project ID Location Age of Field Cores Section # Cores Tested Binder Grade WMA Modified Binder Contains RAP FHWA ALF Virginia 8 years Control-2002-Lane 2 (ACTRL) Read the entire page →
From page 17... ... Refinement of the Climate-Based, Predefined Laboratory Aging Durations 17 uses a solvent mixture of toluene and ethanol (85:15) Read the entire page →
From page 18... ... 18 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results for each year was used to calculate the CAI values, and the averaged data for the 37 years were used in the recalibration effort. The FHWA ALF cores were extracted from sections that had been subjected to high temperatures, which were not realistic, in previous FHWA ALF rutting experiments. Read the entire page →
From page 19... ... Refinement of the Climate-Based, Predefined Laboratory Aging Durations 19 large variability in the measurements taken from the field cores. The noted discrepancies in the relationship between the measured aging durations and the values calculated using the original CAI parameters could reflect differences in the MERRA-2 weather data used herein and the MEPDG weather data that were used to calibrate the original CAI values. Read the entire page →
From page 20... ... 20 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results mixtures shown in Figure 8 (a) Read the entire page →
From page 21... ... Refinement of the Climate-Based, Predefined Laboratory Aging Durations 21 Final Recalibration of the Climatic Aging Index A final recalibration of the CAI was carried out to determine the optimal D values in Equation (4) using least squares optimization to minimize the error between the measured oven aging durations and those predicted by the CAI at each depth after excluding the ALF and LSD sections. Read the entire page →
From page 22... ... 22 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results ALF sections. The results also reflect the depth dependence of field aging relatively well. Read the entire page →
From page 23... ... Refinement of the Climate-Based, Predefined Laboratory Aging Durations 23 between the field and laboratory aging of polymer-modified materials under realistic climate conditions merits further investigation in future work. The data for the WMA sections correspond closely to those of the HMA sections, suggesting that the recalibrated CAI is applicable to WMA mixtures. Read the entire page →
From page 24... ... 24 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results Figure 12. Required oven aging durations at 95çC to match 4 years of field aging for depths of (a) Read the entire page →
From page 25... ... Refinement of the Climate-Based, Predefined Laboratory Aging Durations 25 Figure 12. (Continued) Read the entire page →
From page 26... ... 26 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results Figure 13. (Continued) Read the entire page →
From page 27... ... Refinement of the Climate-Based, Predefined Laboratory Aging Durations 27 (a) 6 mm Depth (b) Read the entire page →
From page 28... ... 28 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results Summary The recalibrated CAI can be used to determine the required laboratory aging durations as a function of hourly pavement temperature history and depth with reasonable accuracy (R2 = 0.78) for HMA and for WMA mixtures without RAP. Read the entire page →

From page 14...

... 14 Research Approach Overview The CAI, which is used to relate the pavement temperature history to the required laboratory aging duration, was recalibrated and simplified using original binders, aggregates, and field cores from selected pavement sections. Emphasis now was placed on other mixture types, i.e., WMA mixtures, mixtures containing RAP, and PMA mixtures, which were not considered thoroughly in the initial calibration of the laboratory aging procedure.