Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results (2021) / Chapter Skim
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29 Research Approach Overview A refined PAM was established in this study by calibrating the kinetics model predictions of field aging using Equation (1) as a function of depth for a wide range of pavement sections, including both conventional HMA and modern materials (i.e., RAP, WMA, and PMA)
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30 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results asphalt content (L) and medium air void content (M)
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Refinement of the Pavement Aging Model (PAM) 31 Project ID Location Age of Field Cores Section # Cores Tested Binder Grade WesTrack Dayton, Nevada 19 years (S4)
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32 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results Figure 16. Setting up gyratory-compacted samples in panels for eld aging in Brazil.
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Refinement of the Pavement Aging Model (PAM) 33 Project ID Location Age of Field Cores Section (Section ID)
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34 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results of each field core were sliced to create four 12.5-mm-thick discs. The remainder of each field core was cut into 25-mm-thick discs.
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Refinement of the Pavement Aging Model (PAM) 35 histories as a function of pavement depth.
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36 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results within a mixture and thus yield increased aging levels. However, as will be shown, the results deviated from these expectations in some cases.
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Refinement of the Pavement Aging Model (PAM) 37 and 4.5 cm, respectively.
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38 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results effect of asphalt type that is expected. However, the air void content was found to have an insignificant effect on field aging of the WesTrack and Brazil field cores.
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Refinement of the Pavement Aging Model (PAM) 39 Relationship Between Kinetics Model Predictions and Smoothed Field Core Measurements The relationship between the kinetics model predictions and the smoothed field core measurements of log |G*
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40 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results Field Calibration of the Pavement Aging Model The field calibration of the PAM is intended to yield a log |G* | gradient with depth and time that meets a number of conditions.
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Refinement of the Pavement Aging Model (PAM)
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42 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results Figure 23 shows AP plotted versus depth starting at time zero and plotted for time increments of 2 years. The hourly pavement temperature history for each depth and time increment is used to calculate AP in this graph.
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Refinement of the Pavement Aging Model (PAM) 43 shown in Figure 22, which is contrary to field core measurements shown in the right column of figures in Figure 20.
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44 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results The parameter b2 represents the maximum log |G* | value that can be achieved at the pavement surface.
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Refinement of the Pavement Aging Model (PAM) 45 where a1 and a2 = regression parameters, and APt=10 = Aging Parameter at the pavement surface at 10 years of aging, kPa.
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46 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results The field-calibrated PAM predictions of the log |G* | values were determined for each project and field core depth using Equation (22)
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Refinement of the Pavement Aging Model (PAM) 47 field-measured log |G*
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0 1 2 3 4 5 6 0 1 2 3 4 5 D ep th (c m )
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Refinement of the Pavement Aging Model (PAM)
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50 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results 0 1 2 3 4 5 6 0 1 2 3 4 5 D ep th (c m )
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Re nement of the Pavement Aging Model (PAM)
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52 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results ( )
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Refinement of the Pavement Aging Model (PAM) 53 greater gradient with depth than all the other sections, which explains the reason that the PAM predictions do not align very well with the field core measurements.
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54 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results original viscosity (ηorig) is available instead of ηt=0, a conversion can be done to obtain ηt=0, as shown in Step 1 of Table 8.
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Refinement of the Pavement Aging Model (PAM) 55 greater predictive accuracy than the GAS model, as illustrated by R2 = 0.7061 compared to R2 = 0.3792.
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56 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results 0 1 2 3 4 5 6 0 1 2 3 4 D ep th (c m ) M15R-4Y Pavement Aging Model GAS (a)
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Refinement of the Pavement Aging Model (PAM)
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58 Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction: Phase III Results convert viscosity to |G* |, the phase angle measured from field cores was utilized along with Equation (24)
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Refinement of the Pavement Aging Model (PAM) 59 Description Equation(s)
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