Effect of aging and blending duration on the degree of blending and performance of recycled hot-mix asphalt (HMA)
Yining Zhang, Kezhong Wang, Hengjin Chen, Bingjian Wang, Wenkai Zhu, Huailei Cheng, Lijun Sun
Abstract
This research explored the effect of aging and blending duration on the degree of blending (DoB) and performance of recycled HMAs, as well as the actual contribution of DoBs to the performance of recycled HMA. Nine groups were designed, including one group designed as “full blending group”; one group designed as “no blending group”; and seven experimental groups designed as “partial blending groups” under the different combinations of RAP materials and blending durations. The volumetric indicators, DoB, moisture susceptibility, high- and low-temperature performance of each group were assessed. It was found that prolonging the blending duration can effectively restore the performance of recycled HMAs containing RAP with serious aging. With the extension of blending duration by 180s, more RAP binder was activated, and the DoB of blended mixes enhanced by around 5%~30%, resulting in about 2%~16%, 8%~21%, and 7%~15% improved in the tensile strength ratio, shear strength, and fracture energy of recycled HMAs. In addition, the result also showed that about 10% increase in DoBs, corresponding to RAP binder activated by about 0.15% in this research, can contribute to around 1%~25%, 5%~16%, and 3%~24% improve in the water stability, high- and low-temperature performance of recycled HMAs, respectively.