Design and Manufacture of Superior Asphalt Binders (Revised): Fid-Bau Portal

Design and Manufacture of Superior Asphalt Binders (Revised)

R. R. Davison / J. A. Bullin / C. J. Glover / J. R. Stegeman / H. B. Jemison

The principal objectives of this study were to use supercritical fractionation of asphalt and a study of fraction properties to gain a deeper understanding of what determines asphalt properties and how the asphalt composition can be manipulated to improve properties. This report describes the first attempts to fractionate asphalt, characterize the fractions and recombine them to produce superior asphalts. A large part of the project involved design and construction of a supercritical extraction unit capable of producing kilogram quantities. Three asphalts were fractionated into eight fractions each. The fractions were characterized by a variety of methods. Surprisingly, nickel and vanadium were distributed essentially uniformly throughout all sizes of asphaltenes. The log of the viscosity of the asphaltene-free fractions varied nearly linearly with the fraction heaviness; the presence of asphaltenes caused a large jump in viscosity. A total of thirteen asphalt blends of AC-10 or AC-20 grade were produced by removing various amounts of the heaviest and lightest materials. Nearly all blends had improved aging indexes and most had equal or better temperature susceptibility. Several showed a 25% improvement in toughness. The results from the first fractionation and reblending work demonstrate significant improvement and excellent potential for further major improvements in asphalt quality. The fractionation methods used in the present work to produce superior asphalts can be readily implemented in refineries.