Effects of Aggregate Size on the Rutting and Stripping Resistance of Recycled Asphalt Mixtures

The objective of this paper was to examine the effect of the nominal maximum aggregate size (NMAS) on the rutting and stripping performance of Georgia asphalt mixtures containing reclaimed asphalt pavement (RAP) mixtures using the Hamburg wheel-tracking device (HWTD). Five NMASs of 25, 19, 12.5, 9.5, and 4.75mm of Superpave mixtures were investigated at three test temperatures of 50, 64, and 70 degrees C. The test results were analyzed in terms of five indexes of rutting and stripping resistance: (1)number of loading passes at failure (NF), (2)rut depth at 20,000 wheel passes, (3)stripping inflection point (SIP), (4)creep slope (CS), and (5)stripping slope (SS). The results indicated that Superpave mixtures containing RAP with large NMAS performed better than those with small NMAS in both rut and antistripping resistance. The relationships between the NMAS and SIP showed high correlation coefficients of more than than 0.86 at 64 degrees C. The test temperatures of 64 and 70 degrees C are appropriate for distinguishing size effect for the mixtures with regard to the three parameters of the number of wheel pass at selected rut depth, SIP, and CS.