Evaluation of Asphalt Binder Performance with Laboratory and Field Test Sections

The current performance-grade (PG) specification for asphalt binders was developed 25 years ago. Over the years, many changes have occurred, including crude oil sources, improved refinery technologies to extract more saturates from crude oil before producing asphalt binders, new additives (such as re-refined engine oil bottoms [REOB], polyphosphoric acid [PPA], bio-rejuvenators), and increased use of reclaimed materials. Consequently, asphalt binders with the same PG may perform completely differently, especially in cracking resistance. Researchers evaluated the performance of asphalt binders engineered with various modification techniques including REOB, PPA, aromatic extracts, bio-rejuvenators, and fatty acids. Both rheological and chemical properties of the engineered binders were characterized in the laboratory. It was found that binders produced with same target PG but with different modification techniques can have quite different rheological and embrittlement properties. The current binder selection catalog should be expanded for different applications, specifically for asphalt overlay mixes. Researchers also surveyed 11 existing field test sections constructed with soft and polymer modified binders and constructed 6 more new test sections around Texas. The plant mixes from these test sections were collected during the construction and then tested in the laboratory for their dynamic modulus, rutting resistance, and cracking resistance. Based on the laboratory test results and field performance data, researchers recommended a new statewide binder selection catalog. The implementation of the recommendation will make pavements last longer as intended.