SPR 14-476: RAP/RAS in Asphalt Pavements

The overall objective of this research is to increase the effective use of recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) in road construction activities in Kentucky. Reclaimed materials, such as RAP and RAS, have been combined with virgin asphalt in bituminous concrete mixtures to reduce overall material costs and to make a more rut-resistant mix. RAP/RAS contains aggregate along with oxidized (aged) binder. In addition to recycling into asphalt paving, RAP has been used elsewhere for embankment construction and as a fill material. Although the use of RAP in embankment construction does not take any advantage of the asphalt cement component, it does, nevertheless, provide an alternative application where no other markets for reuse are readily available or where the RAP may be unsuitable for use in asphalt concrete pavement. The properties of RAP/RAS are largely dependent on the properties of the constituent materials. In 2012, the Kentucky Transportation Cabinet revised their specifications related to the use of RAP/RAS in hot-mix asphalt pavements. The 2012 specification changes the way the amount of recycled material is limited in asphalt mix designs. The new limit is based on the total amount of liquid binder being contributed to the mix from the recycled materials. The impact of this change will be examined during this study. Further, the current practices of other state transportation agencies in relation to the use of RAP/RAS in HMA mixtures and other acceptable applications will be documented to provide guidance to the Cabinet during their effort to increase the effective use of RAP/RAS in Kentucky. Stockpile management practices will be examined and reported upon. This study also will examine documenting RAP/RAS use within Kentucky’s Pavement Management System. This information may include, but not limited to, details concerning RAP/RAS quantities used, sources for RAP/RAS, placement details, and related performance monitoring activities. This study will evaluate the use of RAP/RAS in Kentucky and examine how using recycled asphalt pavement affects construction costs, construction waste, and pavement performance.