Influence of bio-based additives on rap clustering and asphalt binder rheology

The use of high Reclaimed Asphalt Pavement (RAP) content in Hot Mix Asphalt (HMA) allows developing innovative materials for the construction and/or rehabilitation of sustainable infrastructures. The chemo-physical phenomena occurring during production of HMA containing high RAP content should be investigated and considered for the mix design optimization. In fact, when additives are used as rejuvenators of the aged bitumen, these phenomena can be affected causing significant variations in the mixture characteristics. This paper aims at studying the influence of two bio-based additives specifically on RAP clustering, phenomena which can significantly affect the performance of high-content RAP asphalt mixtures. The influence of the two additives on the clusters formation was evaluated as well as how these would change the rheological properties of the recovered binder. Results shows that selected additives decrease viscosity and complex modulus of the aged bitumen, while both of them significantly increase amount of new clusters.