Performance-based design of recycled hot-mix asphalt (HMA) incorporating compaction effort variable

Due to the remarkable ecological and economic benefits, more and more attention has been paid to the technology of reclaimed asphalt pavement (RAP). Currently, the potential risks of thermal and fatigue cracking still restrict the large-scale application of recycled materials. This study regards the number of design gyrations (N-des) as a variable and uses a lower Ndes to design the recycled HMAs with higher RAP percentage, which attempts to compensate for the cracking problems by increasing the asphalt content. Five groups containing RAP content various from 0% to 80% were designed. Combined with the statistical analysis (i.e., Tukey pairwise comparison), the high-/low- temperature properties, fatigue life, dynamic modulus, and environmental impacts of this method were evaluated. It can be seen that recycled HMAs actually do not require as high compaction effort as the unrecycled ones (0% RAP). For the recycled HMAs containing 80% RAP, the Ndes of 60 cycles is sufficient for them to achieve the similar high-temperature resistance as the unrecycled ones (using N-des = 100 cycles). In addition, the results indicate that this method can effectively improve the low-temperature and fatigue properties of recycled HMAs, even at a higher RAP percentage. Specifically, with the decrease of Ndes by 12%, the fracture energy and fatigue life of recycled HMAs can increase by almost 3-18% and 10-20%, respectively. Moreover, the method also has considerable effects on the environment. As the content of RAP increases by 20%, the energy consumption and CO2 emission can reduce by approximately 7-10% and 8-10%, respectively.