Mechanistic Evaluation of Recovered Materials from Recycled Asphalt Pavement: Fid-Bau Portal

Mechanistic Evaluation of Recovered Materials from Recycled Asphalt Pavement

Hossain, Zahid / Solanki, Pranshoo / Zaman, Musharraf

Asphalt concrete (AC) is the most recycled product in the U.S. due to its beneficial effects in terms of the reduced consumption of virgin materials and its environmental stewardship. However, the usage of recycled asphalt pavement (RAP) in Oklahoma is significantly lower than in the neighboring states. This is partly because of its high variability in quality and lack of mechanistic performance data and specifications. Consequently, the current study evaluated rheological properties of binders and mechanical properties of aggregates recovered from four RAPs (two field RAPs and two simulated RAPs). Asphalt binders and aggregates were recovered from these RAPs by following the Abson recovery method and the National Center for Asphalt Technology (NCAT) ignition oven technique, respectively. Furthermore, virgin binders and aggregates used in the simulated RAPs were evaluated. Evaluated asphalt binder properties included the performance grade (PG) and consistency (viscosity and penetration). Evaluated engineering properties of aggregates included gradation, durability (Los Angeles Abrasion), sand equivalent, and acid solubility. As expected, the recovered binders were found to be significantly stiffer than their virgin counterparts. The corresponding increases in the high and low PG grades of the RAP binder compared to the virgin binder were found to be three PG grades and one PG grade, respectively. The recovered binder was about four times more viscous than the virgin binder. Penetration test data of these binders also showed similar consistency trend. Mechanical properties of RAP aggregates were found to vary significantly, which could be related to sampling and processing of RAP. Gradation data of aggregates showed a notable increase in fine contents in the RAP aggregates compared to the virgin materials. Also, Los Angeles Abrasion loss and sand equivalent values of RAP aggregates were found to be significantly higher than those of the virgin counterparts. The findings of this study are expected to beneficial to the pavement professionals for the evaluation of RAP.