Evaluate the Impact of the Reclaimed Asphalt Pavement (RAP) Binder Activation on its Shape Properties

The degree of binder activation of reclaimed asphalt pavement (RAP) is one of the main points that affects the design of the recycled asphalt mixture (RAM). Most previous works concentrate effort analyzing the degree of binder activity (DoA) from the asphalt binder point of view. However, there is lack of existing information about the impact of the DoA on the aggregate’s properties. Assuming DoA less than 100%, which is the most used assumption on the literature, means that part of the RAP binder will be inactive, so it is unclear which RAP aggregate properties, such as gradation and shape, should be used to design the RAM. In this context, the main objective of this work is to understand the impact of the DoA on the RAP’s aggregates properties. Stages of binder extraction were performed in two RAPs in order to simulate different DoAs. After each stage of binder extraction, the RAPs were analyzed using digital image processing (DIP). The results indicate that RAPs with the same gradation present distinct size distribution after each stage of extraction mainly due to the clusters present on the RAP. RAP angularity is affected by the DoA, especially for coarse aggregates. Thus, the DoA affects not only the binder available to be blending with the virgin binder but it also can affect the aggregate mineral skeleton of the RAM.