Effects of Temperature and Shear Rate on Viscosity of Sasobit®-Modified Asphalt Binders

In this study, Superpave gyratory compacted samples were prepared at different compaction temperatures, at different asphalt contents and at different number of gyrations to evaluate the effects of Sasobit® on density of asphalt mix. Dynamic viscosity was measured at temperature ranges from 28°C to 130°C at 6°C interval. From density and viscosity analyses it can be concluded that there exists a critical temperature for a Sasobit® modified asphalt binder such that above the critical temperature Sasobit® reduces the viscosity as well as increases density and below that temperature Sasobit® increases the viscosity as well as reduces the density. Also, the shear rate dependency of steady state viscosity of asphalt binders with and without Sasobit® was analyzed in this study within the range of 0.0025/s to 250/s. With the addition of Sasobit®, PG 64-22 at 64°C becomes a shear-thinning liquid. The shear rate dependency increases with an increase in percent of Sasobit®. Similar effects of Sasobit® are observed at 100°C in reduced level and shear rate dependency with the addition of Sasobit® is almost negligible at 124°C. Also, the rate of change of viscosity is higher at higher shear rates and lower at lower shear rates. For PG 76-22M, the shear rate dependency increases with an increase in percent of Sasobit® at all the three temperatures. This indicates that if the actual shear rate in the field is higher than what is used for viscosity measurements, the mixing and compaction temperatures currently being used can be reduced. Also in this study, the steady state viscosity data were fit to a simplified CROSS model and the fitting was evaluated by the coefficient of determination values. The zero shear viscosity at 64°C and 76°C were determined for PG 64-22 and PG 76-22M, respectively. Comparative studies between zero shear viscosity and G*/sinδ at various temperatures, dynamic viscosity and steady state viscosity at various temperatures were also conducted.

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  • Accession Number: 01457638
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Dec 20 2012 9:14AM