Development of Rutting Model for Unbound Aggregates Containing Recycled Asphalt Pavement

The use of recycled materials for construction is beneficial to both the environment and the economy. Recycled asphalt pavement (RAP) is one of the most commonly used recycled materials. Different state departments of transportation allow the use of RAP in base materials using various RAP percentages. Unlike conventional crushed aggregate, RAP exhibits a high resilient modulus, but also low resistance to permanent deformation, which contradicts the relationship between the modulus and permanent deformation in the permanent deformation model for unbound materials found in the mechanistic-empirical pavement design guide (MEPDG). In this study, repeated triaxial tests are conducted on samples containing different percentages of RAP and crushed aggregate. Permanent deformation prediction models for granular base course materials, introduced in 1989 by Tseng and Lytton, are modified by adding the RAP percentage as a parameter for base course materials containing RAP. The results indicate that the proposed model accounts for the effects of RAP reasonably well. Further studies are needed to validate the new rutting model by including different virgin aggregates and RAP mixtures under various testing conditions.