Multi-performance evaluation of recycled warm-mix asphalt mixtures with high reclaimed asphalt pavement contents

The recycled warm-mix asphalt (RWMA) technique is advanced in increasing the reclaimed asphalt pavement (RAP) content of the recycled mixture and mitigating the secondary aging of the RAP binder. However, the effects of this technique on the mixture performance need to be further investigated, as existing findings tend to be inconsistent and may bias the RWMA's engineering application. In this research, multi performances (moisture susceptibility, low-temperature, high-temperature, fatigue) of RWMA mixtures prepared with various design components, i.e., RAP contents (50% and 70%), WMA additive (wax R and surfactant M) and gradation (AC-13 and AC-16), were assessed. It was found that increasing RAP content reduces the moisture damage resistance and low-temperature performance of RWMA mixtures, and these reductions can be compensated by using WMA additives. By contrast, the rutting resistance and fatigue performance of the RWMA mixture rise as the appropriate combination of WMA additive and RAP content is adopted. The analysis of variance (ANVOA) statistical analysis was conducted to quantitatively assess the impacts of different design components on RWMA performances. It was observed that the RAP content had the predominant impact on most of the performance of RWMA, while the WMA additive type dominantly influences the moisture susceptibility of the mixture. The gradation type only has a slight effect on the moisture susceptibility of the RWMA, but shows a predominant impact on its high- and low-temperature performance. The nomographs for multi-performance indicators were also derived to reveal the variation trends of different RWMA performances with the changing design components. These findings are expected to provide references for regulating multi performances of RWMA by adjusting the appropriate design components.