Comparative Field Performance of Asphalts from Multiple Crude Oil Sources

Abstract

A comparative pavement performance site was built in 2001 in central Arizona with four unmodified PG 76-16 asphalts. The four asphalts from different crude oil sources and blends were used to build sections of pavement about three-quarters of a mile long. All other variables (e.g., aggregate source and gradation, geometric and structural design, traffic, climate, and compaction) were held as constant as possible. In a typical project, a construction contractor could have purchased any of the four asphalts because all met the project specifications. Before construction of this site, a search was conducted for existing projects for which the asphalt source was varied and location documentation and original construction materials were available. No such projects were found. The mission was to acquire real-world, long-term pavement performance data for asphalts from different crude oil sources so that the validity of existing and new long-term performance predictive test methods could be examined. The focus was on performance variations related to asphalt crude oil source and thus asphalt compositional features. Several chemical and rheological tests were performed on the asphalts to gain information to relate to field performance. The four asphalt sources showed remarkable differences in performance. Similar comparative pavement performance sites were located in Wyoming, Nevada, Arizona, Kansas, Minnesota, and the Yellowstone National Park east entrance. All sites are monitored annually.