Investigation of the Performance of 100 Reclaimed Asphalt Pavement Mixtures: Molecular, Chemical, and Mechanical Characterization

摘要

The demand for sustainability in the asphalt industry has resulted in the use of higher levels of RAP materials in new pavements. The addition of rejuvenators in mixtures containing RAP has the potential to increase the quantity of said RAP materials. The performance of these mixtures depends on the extent to which the rejuvenators can restore RAP asphalt binder properties to levels comparable to virgin asphalt binder. The objective of this study was to compare the molecular structure and chemical properties of rejuvenated 100% RAP binders and mixtures with their rutting and intermediate temperature cracking potential. Two experimental factorials (i.e., asphalt binder and mixture experiments) were conducted. In the first experiment, binders were extracted from 9.5 mm NMAS 100% rejuvenated RAP mixtures. The 100% RAP mixtures were rejuvenated using the following parameters: (1) two rejuvenator types (RA1 and RA2); (2) two dosage rates (7.9 and 15.7% for RA1 and 6.5 and 11.3% for RA2); and (3) three aging levels (short-term aged 1hr, 165°C: long-term aged 5-, and 10-days, 85°C). Gel Permeation Chromatography, Fourier Transform Infrared Spectroscopy, and Iatroscan Analyses were combined with rheological evaluation (Glover-Rowe Parameter) for the characterization of the asphalt binders. The second experiment was conducted on a 9.5 mm NMAS asphalt mixture prepared with 100% RAP materials that were rejuvenated using the parameters described in the first experiment. The mixtures were characterized using Loaded Wheel Tracking (LWT) and Semi Circular Bend (SCB) tests at high- and intermediate-temperatures, respectively. Generally, changes in the distribution of associated asphaltenes in 100% RAP mixtures subjected to the aging protocols considered could be identified using GPC. Redistribution of the higher molecule weight species was observed, which reduced the stiffness of the mix and thus improved the cracking resistance. Generally, 100% RAP mixtures with high rejuvenator dosage rates produced materials with high maltene contents that exhibited lower rutting resistance.