Evaluation of a biofuel residue-derived recycling agent with a low carbon footprint

Abstract

Protecting environment, conserving natural resources by recycling and replacing non-renewable materials with renewable ones, reducing material cost, and utilizing sustainable processes are actively pursued by asphalt industry. Consistent with those efforts, Recycling Agents (RAg) with different technologies have been introduced which allow using high amounts of Reclaimed Asphalt Pavement (RAP) in construction of new pavements. RAgs, depending on their type and chemical composition, affect the mechanical properties of the asphalt binders differently. This study was undertaken to characterize effectiveness of using a relatively new plant-based RAg produced from biofuel residue in a low-carbon footprint process when used in asphalt binder blends containing a high amount of RAP. Effects of using different amounts of RAg, namely 0, 4, 6, and 8% (by binder weight) incorporated in a blend of a PG 58-28 containing 30% laboratory-simulated RAP binder (RAPsb) on binder blends’ rheological properties were studied by testing them in a dynamic shear rheometer and a bending beam rheometer and by conducting Multiple Stress Creep Recovery (MSCR) tests. In addition, effect of using RAg by its optimum dosage in a blend of PG 58-28 binder containing 30% RAPsb on its adhesion with granite and quartzite aggregates and moisture-induced damage was characterized. As a result, a Superpave grade of PG 58-34 was found to be achievable by incorporating 4% RAg in a blend of PG 58-28 and 30% RAPsb. Also, incorporating 4% RAg in a blend of PG 58-28 and 30% RAPsb improved the fatigue resistance of the RAPsb-laden binder to an extent which exceeded that of the neat PG 58-28. Furthermore, an elastic recovery response significantly higher than and a non-recoverable creep response equivalent to those observed in neat PG 58-28 were achieved by incorporating 4% RAg in a blend of PG 58-28 and 30% RAPsb, both having an MSCR grade of PG 58S. Finally, an overall improvement in resistance to moisture damage in PG 58-28 binder containing 30% RAPsb with granite and quartzite was observed as a result of incorporating 4% RAg in the blend.