Development of Blending Chart for Different Degrees of Blending for Reclaimed Asphalt Pavements in HMA

The demand to utilize higher percentages of reclaimed asphalt pavement (RAP) in the construction of hot mix asphalt (HMA) pavements continues to rise. Utilization of RAP in HMA is an environmentally friendly and cost effective method of recycling. At high percentage of RAP properties of RAP binder and its interaction with virgin binder plays critical role. Researchers have consistently shown that when RAP is mixed with virgin binder and aggregates, partial blending occurs, that is, something between 100% blending and the "black rock" effect occurs. Impact of partial blending on new virgin binder content is apparent which may cause under-asphalted mixture, resulting in poor pavement performance. Also influence of partial blending on final grade of RAP mix and allowable percentage of RAP has not been evaluated. The purpose of this paper is to develop the blending chart for different degree of blending to study the impact of partial blending on final grade of blended binder. To achieve the objective, blending chart for 100%, 70% and 50% RAP has been developed for PG 70-28 and PG 58-28 binder by carrying out binder study.