COMPOSITIONAL EVALUATION OF ASPHALT BINDER RECYCLING AGENTS

ABSTRACT

The results presented here indicate that it is possible to produce a high quality binder from hardened recycled asphalt by blending with recycling agents. The properties are presented in terms of Superpave grade and the hardening susceptibility (HS) which is defined as the slope of log viscosity versus infrared measured carbonyl area.

First it is shown that the effect of blending aged binder with aromatic agents is to decrease the HS in rough proportion to the amount of aromatic added and this is only slightly dependent on the aromatic source. The presence of saturates in the agent increases the HS. Using an AC-10 asphalt as the softening agent produced much higher HS values. Adding increasing amounts of aromatic agents on the other hand worsens the Superpave performance grade span. The addition of saturates to the agents has little effect on the span but shifts the span to lower temperature. Though increasing amounts of aromatic agents tended to decrease the grade span, in most instances the span was equal to that produced by blending the aged binder with the AC-10. The hardening susceptibility of the aromatic blends was better than that of the AC-10 blends and better even than the original asphalt.