SUPERPAVE RAP MIXTURES

摘要

NCHRP Project 9-12, Incorporation of Reclaimed Asphalt Pavement (RAP) in the Superpave System, investigated the effects of RAP on binder and mixture properties and the question of whether RAP is a "black rock" or whether blending occurs between the new and RAP binders. Shear testing results presented here demonstrate the effects of adding RAP to a mixture when the overall aggregate gradation is held constant. In general, adding RAP to a mixture increases the shear modulus and decreases shear strain and maximum shear deformation. At low RAP contents, however, the effects are not significant. These results support the earlier Mixture Expert Task Group recommendations for using a three-tiered approach for Superpave RAP mixtures, though some adjustment in the limits for the tiers may be appropriate. The paper concludes with a discussion of the possible impacts of wide scale adoption of this approach on HMA contractors.