Evaluation of low-temperature binder properties of warm-mix asphalt, extracted and recovered rap and ras, and bioasphalt

This research project evaluates the low-temperature performance of energy-efficient and environmentally friendly hot-mix asphalt (HMA) paving materials. Innovative materials gaining interest in the asphalt pavement industry includes warm mix asphalt (WMA), recycled asphalt shingle (RAS), reclaimed asphalt pavement (RAP), and bioasphalt. The materials are used as modifiers in typical HMA to enhance low-temperature field performances. Sasobit compounds at 0.5, 1.0, and 1.5%, by weight of performance grade (PG) 52-34 asphalt binder, are used to design the WMA. Five and 10% of RAS were also added to a PG 52-34 asphalt binder. 50% of RAP combined with 50% of the base PG 58-28 binder, and 100% RAP extracted from the PG 58-28 HMA, were prepared and tested. Bioasphalt was produced from swine waste and used to modify PG 64-22 asphalt binder. By using the Superpave bending beam rheometer (BBR) and the new asphalt binder cracking device (ABCD) method, the thermal cracking performance of the samples were tested. The results showed that (1) the ABCD method can be used alongside or as a confirmation test for the BBR in evaluating the low-temperature cracking resistance behavior of asphalt binders; (2) adding WMA beyond a certain percentage could potentially reduce the low-temperature cracking performance of asphalt binders; and (3) swine waste bioasphalt can enhance low-temperature asphalt binder performance.