Effects of Binder Content, Density, Gradation, and Polymer Modification on Cracking and Rutting Resistance of Asphalt Mixtures Used in Oregon

Abstract

Fatigue cracking performance of asphalt mixtures is highly influenced by the binder and air-void contents, binder grade, binder modification, volumetrics, recycled asphalt pavement/reclaimed asphalt shingles (RAP/RAS) content, and aging. In Oregon, asphalt pavements commonly fail prematurely due to cracking-related distresses, necessitating costly rehabilitation and maintenance at intervals of less than half of the intended design lives in some cases. This study focuses on characterizing the cracking performance of asphalt mixtures used in Oregon by evaluating the impact of asphalt mixture variables, such as binder content, air-void content, aggregate gradation, and polymer modification, on cracking and rutting performance using semicircular bend (SCB) and flow number (FN) tests, respectively. The goal of this study is to provide a better decision-making structure during the pavement design stage to address fatigue cracking susceptibility, with the intent of avoiding premature pavement failure and expensive early maintenance and rehabilitation. Increased binder content improved the cracking performance, suggesting that increasing binder content of asphalt mixtures currently used in Oregon can create significant savings by improving pavement longevity. Additionally, reducing the density increases cracking performance; therefore, producing asphalt mixtures that are easy to compact and utilizing intelligent compaction technologies that are currently being implemented in Oregon can potentially create a significant improvement in the fatigue cracking resistance of asphalt mixtures.