Volume 9, Issue 2 (February 2012)
Influence of Recovery Processes on Properties of Binders and Aggregates Recovered from Recycled Asphalt Pavement
Usage of recycled asphalt pavement (RAP) in the construction of new pavements has increased in recent years due to the movement to conserve energy and raw materials, and reuse waste materials. To assess the effectiveness of RAP materials in new asphalt mixes, it is important to evaluate the properties of the recovered binders and aggregates. The widely used “Abson” method is employed in this study to recover asphalt binder from RAP. Also, the frequently used “NCAT ignition” method is used to extract aggregates. A laboratory study comprising two field RAP materials, two simulated RAP materials, and corresponding virgin materials was undertaken to assess possible influences of the aforementioned recovery processes. The performance grade (PG) of the recovered binders, and gradation, durability (LAAbrasion and Micro-Deval), specific gravity, sand equivalent, and insoluble residue of the extracted aggregates were evaluated as per the AASHTO and Oklahoma Dept. of Transportation (ODOT) standards. The test results showed that the Abson method notably influenced the critical PG temperatures of the recovered binder. It was also observed that some mechanical properties (durability and sand equivalent) of RAP aggregates were inconsistent with their virgin counterparts. Furthermore, field RAP aggregates showed significant variations in LA Abrasion loss and insoluble residue test results. The findings of this study are expected to be helpful in the evaluation of RAP for reuse in asphalt paving.