Evaluation of Asphalt Binder Rejuvenators for Use in Recycled Asphalt

Recycled materials, both reclaimed asphalt pavements (RAP) and reclaimed asphalt shingles (RAS) are used to reduce the cost of some hot mix asphalt (HMA) mixtures. These materials lessen the amount of virgin material needed for a surfacing project and can reduce the amount of material that otherwise would be disposed of in landfills. South Dakota Department of Transportation (SDDOT) does not allow the use of RAS, therefore only RAP will be considered in this project. One concern about using RAP in asphalt concrete pavement is that the binder in the reclaimed material is less flexible than virgin binder and may reduce the cracking resistance of the mix. Because of this, SDDOT currently allows the use of only 20 % RAP by weight of aggregate in mainline mix designs. Products known as asphalt binder rejuvenators claim to increase flexibility in reclaimed asphalt binder and allow higher percentage of RAP to be used. This is sometimes referred to as “softening” the reclaimed binder. The purpose of this research will be to evaluate the effectiveness of a number of these rejuvenators with South Dakota conditions and materials. The study seeks to determine if rejuvenators increase flexibility of recycled binders when used in HMA and what effects they have on asphalt mixes later in the life of the pavement. A protocol will be developed to allow rejuvenators other than those included in this study to be evaluated. The objectives of this research are to: (1) Compile and evaluate data on the state of practice for use of recycled asphalt binder rejuvenators; (2) Develop a testing protocol or procedure that can be used to evaluate recycled asphalt binder rejuvenators; and (3) Evaluate a minimum of 5 binder rejuvenation products that could routinely be used in South Dakota.