Laboratory performance analysis of high percentage artificial RAP binder with WMA additives

- Performance tests were conducted using high percentages of artificial RAP binder and two WMA additives.
- The relationship between RAP contents and performance test results was analyzed.
- The artificial RAP content had little effect on the BBR test results.
- Both artificial RAP content and WMA additive type affected the performance of recycled binders.

Warm mix asphalt (WMA) technology particularly involving high percentage of reclaimed asphalt pavement (RAP) has become more commonly used due to its promising advantages in environment, energy cost and workability. This paper focuses on the laboratory performance investigation of recycled binders containing high percentage artificial RAP binder (up to 70%) with incorporation of two types of WMA additives, i.e., polyethylene wax (R) and surfactant (M). The artificial RAP binder was obtained through rolling thin film oven (RTFO) and pressure aging vessel (PAV) aging to ensure its pure source and known properties. The rotational viscometer (RV), dynamic shear rheometer (DSR) and beam bending rheometer (BBR) tests were carried out on the recycled binders. The results indicated that when the percentage of the artificial RAP binder was up to 70%, the performance still satisfied the requirements of the Superpave binder specifications. In addition, both the artificial RAP binder content and the type of WMA additives played an important role in determining the performance of recycled binders with WMA additives. Typically, the WMA additive R and artificial RAP binder could offset the disadvantages of each other in rutting and fatigue resistance respectively. Moreover, most of the test results exhibited obvious linear or exponential trends with the artificial RAP binder content. However, the increase of the artificial RAP binder content had little influence on the BBR test data.