Dynamic and rutting characteristics of recycled asphalt mixtures containing natural sand and anti-stripping agents

Abstract

The combined utilization of Recycled Asphalt Pavement (RAP) and natural sand as alternative aggregates was attractive for potential environmental and economic benefits. The dynamic and rutting performances of recycled asphalt mixtures containing natural sand and Anti-stripping Agents (ASAs) were investigated in this study. Two mixture types (Surface Type B with Ndesign of 75 and Surface Type C with Ndesign of 50), two aggregate sources (designated as J and L), and three ASA types (designated as A0, A1, and A2) were designed. In addition, 23% and 27% RAP was respectively selected for Surface Type B and C mixtures, and 20% natural sand was designed for all the mixtures. The results indicated the Surface Type B mixtures generally had higher dynamic modulus and lower phase angle than the Surface Type C mixtures. Mixtures prepared by aggregate J had greater engineering performance than aggregate L. The effect of ASA type was insignificant on these mixtures made by aggregate J, while the liquid ASAs were more effective than hydrated lime for those fabricated by aggregate L. In terms of rutting resistance, the findings from APA tests agreed with HWT tests in most cases, indicating the limited use of RAP and natural sand was proved to be satisfactory. In addition, the use of ASAs was highly effective to prevent the recycled mixtures from moisture damage. Finally, the dynamic modulus at 37.8 °C and 54.4 °C used a loading frequency of 5 Hz statistically correlated with the APA and HWT rut depth.