The Impact of the RAP Cluster Dissociation on Gradation and Shape Properties of Aggregates from Recycled Asphalt Mixtures
Abstract
The presence of clusters in reclaimed asphalt pavement (RAP) is a critical point that affects the RAP homogeneity. In this phenomenon, different RAP particles are working together as a single aggregate. The cluster dissociation occurs during hot asphalt mixture production and compaction in the field. This research is concerned with the impact of the cluster disintegration on the recycled asphalt mixture aggregate properties. Stages of binder extraction were performed in six RAP materials to partially activate the RAP binder and create different levels of cluster dissociation from 0 to 100 %. Then, the gradation curve and the aggregate shape properties were obtained for each level. Using a gradation curve (without RAP) as a reference, a hypothetical recycled asphalt mixture was created with different RAP percentages to investigate the impact of cluster dissociation on the aggregate properties of the recycled mixture. The results indicate that the RAP aggregate properties are significantly affected by the cluster dissociation. Besides, there was a significant impact on the partial cluster dissociation, because of RAP-binder activation, on the gradation curve and aggregate shape of the recycled mixture, mainly when the level of RAP-binder activated is between 40 and 70 %.