Rheological and physico-chemical properties of warm-mix recycled asphalt mastic containing high percentage of RAP binder

Abstract

Abstract The present study investigated rheological and physico-chemical properties of warm-mix recycled asphalt mastics containing a high percentage (50%) of artificial reclaimed asphalt pavement (RAP) binder. The influence of two typical warm-mix additives (a wax-based R and a surfactant-based M), four mass ratios of filler to asphalt (0.0–1.5), and three aging states (unaged, short-term aged and long-term aged) was evaluated through the dynamic shear rheometer (DSR), bending beam rheometer (BBR), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) tests. A total of 48 different mastics were tested and analyzed. The results showed that both the increasing RAP binder and filler contents had a stiffening effect on the asphalt mastics over the full range of testing temperatures and significantly reduced the linear viscoelastic strain limits of the mastics. The two warm-mix additives played quite different roles in changing the rheological properties of the mastics. Overall, the addition of the wax-based R exhibited a softening effect on the mastics and thus was capable of offsetting the stiffening effect of applying the RAP binder and mineral fillers; whereas the impact of the surfactant-based M on the rheological properties of the mastics was found negligible. The difference of R and M in working mechanisms could be clearly characterized using the chemical FTIR spectra.