Evaluation of rutting properties of asphalt binders and mixtures with tire pyrolytic char

Abstract

Waste or end-of-life tires are generated in huge quantities all over the world and pose a serious challenge for the environment. Pyrolysis is a quite effective chemical route for recycling of waste tires, and produces three-phase products: liquid pyrolytic oil, gases, and solid tire pyrolytic char (TPC). The TPC is generally considered a by-product of waste tire pyrolysis process and has recently gained interest as an additive/modifier to road asphalt binders. Rutting in thick asphalt layers is a commonly observed distress on heavy-duty flexible pavements, which are quite preferred in India as well as throughout the globe. Rutting in the asphalt-bound pavement layers refers to the accumulation of permanent deformation under the influence of high pavement temperatures and heavy traffic. Asphalt binders play a significant role in imparting rutting resistance to an asphalt concrete pavement layer. Evaluation of rutting resistance of TPC modified binders and mixtures is thus quite important to support its wide-spread use in construction of asphalt pavements. This study first evaluated the rutting performance of TPC modified binders (prepared at five TPC contents) at multiple temperatures (40, 50, 60, and 70 °C) and stress levels through five rheological parameters: (1) Superpave rutting parameter; (2) Shenoy rutting parameter; (3) zero shear viscosity; (4) non-recoverable creep compliance (Jnr) from multiple stress creep and recovery (MSCR) test; and (5) non-recoverable strain rate ( εnr ) from the MSCR test. A dynamic shear rheometer was used to measure the TPC modified asphalt binder rutting characteristics. Asphalt mixtures were then fabricated using the TPC modified binders and evaluated for rutting performance using the Hamburg wheel-tracking device. Correlation analysis was performed for binder rutting parameters and mixture rut depth. Overall, the findings indicate that the addition of TPC enhances the rutting performance of both asphalt binders and the asphalt mixtures.