Asphalt recoveries by the abson and roto-vap methods were performed at various temperatures and for several asphalt viscosities. Solvent (trichloroethylene, tce) concentrations after recovery were measured by gel permeation chromatography. Asphalt viscosities and residual solvent concentrations during solvent removal were determined for tank, over-aged, and solvent-exposed asphalt to evaluate the effectiveness of the procedures and operating parameters. Small amounts of solvent cause significant decreases in viscosity, and present recovery methods do not remove solvent adequately. In general, recoveryrates increase strongly with temperature in both methods. High viscosities and larger asphalt samples hinder solvent removal rates in the abson method. Asphalt hardens significantly on extended exposure to tce at both 200 deg f and 80 deg f. This hardening also occurs during solvent removal processes, but removal at a reduced temperaturethrough use of a vacuum in the early stages can inhibit it. This paper appears in transportation research record no. 1269, Asphalt mix materials and mixtures 1990.
Abstract