Effect of rejuvenator types and mixing procedures on volumetric properties of asphalt mixtures with 50% RAP

The use of Reclaimed Asphalt Pavement (RAP) in asphalt mixtures has several benefits, such as reducing the consumption of virgin materials and protecting the environment. However, as high RAP content (e.g., 50%) is used, asphalt mixtures become brittle so that premature failure (cracking) may occur. To improve the cracking resistance of asphalt mixtures with high RAP contents, one of the approaches considered is the use of rejuvenators. Such rejuvenators, when used in high RAP asphalt mixtures, counteract the effects of the aged RAP binder and may have an impact on the volumetric properties of the mixtures. The objective of this study is to evaluate the effect of rejuvenator types and mixing procedures on the volumetric properties of asphalt mixtures prepared with high RAP content (i.e., 50%). To achieve this objective, three rejuvenators and three rejuvenator mixing procedures were utilized to prepare asphalt mixtures containing 50% RAP. Volumetric properties of the mixtures (air voids (AV), voids in mineral aggregate (VMA), and dust to binder ratio) were determined. Testing results indicate that some volumetric properties of mixtures (AV and VMA) could significantly change when different mixing procedures and rejuvenator types were used. Therefore, the mixing procedures and the rejuvenator types should be taken into considered when conducting mixture design.