Research on pavement performance of recycled asphalt mixture based on separation technology of asphalt and aggregate in RAP

Asphalt-aggregates separation of reclaimed asphalt pavement (RAP) with bio-oil as solvent is an economical, simple, and efficient method to recycle RAP materials. The byproducts of asphalt-aggregates separation of RAP are recycled aggregates and blends of bio-oil and old asphalt (BBOA). In this paper, to improve the recycling rate of BBOA and recycled aggregate after asphalt aggregate separation, Buton Rock Asphalt (BRA) is used as a high-temperature property modifier to compensate for the aging resistance and high-temperature of BBOA. The physical properties of rock asphalt modified bio-oil asphalt (RMBA) with different amounts of BBOA were studied by viscosity, frequency scanning, multiple stress creep, bending beam rheology, and aging tests. At the same time, recycled aggregates of different particle sizes and RMBA were used to prepare asphalt mixture with diverse mix design methods. The pavement properties of the recycled asphalt mixture were evaluated by rutting resistance, low-temperature bending beam, freeze–thaw splitting, and fatigue tests. The results show that RMBA realizes the complementary advantages of BRA as a high-temperature modifier and BBOA as a low-temperature performance modifier. The recommended dosage of RMBA is 20 %rock asphalt and 7 %BBOA. Under different preparation methods, the pavement performance of rock asphalt modified bio-oil asphalt mixture, asphalt mixture containing coarse recycled aggregate, and asphalt mixture containing oil sand meet the requirements of asphalt pavement design specifications, the preliminary realization of 100% recycling of RAP.