Multiple Stress–Creep–Recovery Behavior and High-Temperature Performance of Styrene Butadiene Styrene and Polyacrylonitrile Fiber–Modified Asphalt Binders

Asphalt binders and concretes modified with polyacrylonitrile (PAN) fiber, styrene butadiene styrene (SBS), and the combination of PAN-SBS were prepared and studied. Both frequency and temperature sweep tests for the binder dynamic shear modulus G*, rutting, and fatigue parameters were carried out. Multiple stress creep recovery (MSCR) test was also conducted on the various modified asphalt binders. The complex modulus E* and flow number (FN) of asphalt concretes (AC) from the modified binders were also examined using asphalt mixture performance tester (AMPT) test. The PAN fiber asphalt binder showed better response in terms of dynamic modulus, fatigue and rutting parameter, nonrecoverable creep compliance and percent strain recovery at 1% fiber content. The hybrid binder (1%PAN+1%SBS) demonstrated overall shear modulus almost twice that exhibited by 2%SBS binder. The hybrid asphalt binder showed the greatest potential for rut resistance, over most of the frequency range, relative to all other binders. It was clear that the combined form of the polymer and the fiber modification has greater rutting resistance potential than the single modification approach generally practiced. The hybrid asphalt binder also showed better fatigue parameter than all the binders within pavement design load frequency range. Results from the AC mix tests verified most of the trends observed from the asphalt binder tests.