Effects of nominal maximum aggregate size and compaction effort on the mechanical properties of hot-mix asphalt (HMA)

Considering the potential rutting distress and excellent fatigue performance of small nominal maximum aggregate size (NMAS) mixes, this study explored the function of number of design gyrations (N-des) variable in the design, and attempted to balance the high-temperature and fatigue performance of these materials. Therefore, one experimental group (9.5 mm NMAS mixes under N-des = 80 cycles) and three control groups (9.5 mm/13.2 mm/16 mm NMAS mixes under N-des = 60 cycles) were designed. The uniaxial penetration shear test, the uniaxial compressive modulus test, the British pendulum test, the indirect tensile cracking test, and the indirect tensile fatigue test were then conducted. It can be found that through increasing the N-des by 20 cycles, the rutting resistance of 9.5 mm NMAS mixes improved significantly, and can reach the same level as that of 13.2 mm NMAS mixes. Moreover, under this design, the 9.5 mm NMAS mixes can still perform a longer fatigue life than 13.2 mm NMAS mixes. In addition, increasing the N-des also helps to improve the cracking resistance and dynamic modulus of these materials. Specifically, with the increase of N-des by 20 cycles, the fracture energy and dynamic modulus of 9.5 mm NMAS mixes can improve by almost 516 J.m(-2) and 1860 MPa (10 Hz and 21 degrees C), respectively. These results may indicate that selecting a suitable N-des is helpful to balance the properties of small NMAS mixes.