Effect of design parameters on degree of blending and performance of recycled hot-mix asphalt incorporating fine reclaimed asphalt pavement particles

Due to the rich binder content and high economic benefits of fine reclaimed asphalt pavement (RAP) particle, more and more attention has been paid to the effective design of recycled hot-mix asphalt (HMA) incorporating this material. This research explored the effect of design parameters on degree of blending (DoB) and performance of recycled HMAs incorporating fine RAP particles. Six groups of mixes were designed, including one no blending group, four experimental groups, and one full blending group. The different parameters of preheating temperature, compaction effort, asphalt content (AC), and blending duration, were involved in this research. It can be found that the recycled HMAs incorporating fine RAP particles under the traditional design proved to the risks in water stability and low-temperature performance. By rising the preheating temperature, decreasing compaction effort and increasing AC, or extending the blending duration, more RAP binder would be activated and blended with the virgin binder, and the poor rheological performance of recycled HMAs can be restored. The different design parameters have different effects on the performance. Besides, the actual contribution of DoB to performance was quantified. With an increase in DoB by 10%, the tensile strength ratio, shear strength, fracture energy, fracture strength, and abrasion loss percentage of recycled mixes can improve by around 15%∼28%, 0.15–0.34 MPa, 180–1969 J·m2, 0.25–0.34 MPa, and 7–18%, respectively. In addition, design incorporating fine RAP particles generally can bring significant advantages in energy consumption and CO2 emission.