American rock asphalt, Devulcanized rubber, Composite modified asphalt, Performance evaluation, Modification mechanism, Materials of engineering and construction. Mechanics of materials, TA401-492

Rock asphalt (RA) has gradually been recognized as a green and efficient asphalt modifier. However, the weakness of low-temperature performance and fatigue resistance for RA modified asphalt limited its application and popularization in asphalt pavement. To overcome the above shortcomings, this study aimed to synergistically apply devulcanized rubber powder (DRP) with American rock asphalt (ARA) for asphalt modification. Multiple experiments such as dynamic shear rheology (DSR) and bending beam rheology (BBR) were conducted to evaluate the rheological properties and road performance of composite modified asphalt (CMA). Cigar tube test (CTT) was applied to assess storage stability of CMA. In addition, Fourier transform infrared spectrometer (FTIR) and microscopic test (MT) were used to investigate the modification mechanisms. The results showed that CMA modified by DRP and ARA exhibited comparable storage stability, low-temperature performance and rutting resistance as SBS modified asphalt. ARA tended to cause aging problems of asphalt, but the addition of DRP effectively improved the aging resistance performance of modified binder blends, especially long-term aging resistance. The mixing of DRP, ARA and base asphalt is a physical process without chemical reactions. Even though the ash in ARA slightly lowered its storage stability, it significantly improved dispersion and homogenous interface of DRP in asphalt.