Use of high percentage of Reclaimed Asphalt Pavement (RAP) material in Hot Mix Asphalt is one of the several sustainable construction alternatives being considered by many Departments of Transportation (DOT). Use of RAP in HMA helps in reducing the consumption of virgin aggregates and binder and construction cost and conserving energy. Although most of the US state agencies allow the use of 30% or more RAP in the design of Hot Mix Asphalt (HMA), the current average RAP usage is only about 10 to 20%. This is because of the uncertainty about the performance of HMA mixes with a high RAP content. Several factors influence the performance of the HMA mixes with a high RAP content. Recent research has shown that the use of a high RAP content in HMA with rejuvenators is successful in reducing the stiffness of the RAP mixes, and thereby improving their performance. The present work is carried out to explore the feasibility of using a high RAP content of 50% in a binder layer HMA with the addition of rejuvenators. Ultrasonic Pulse Velocity (UPV) test was carried out to compare the stiffness of the RAP mixes with and without the addition of rejuvenators. Moisture Induced Stress Test (MIST) was conducted to study the effect of moisture damage on the HMA mixes with high RAP content. The Indirect Tensile Strength Test (ITS) was used to determine the strength of the HMA mixes with high RAP content. In addition, creep compliance and Semicircular Bend (SCB) tests were carried out to determine the cracking potential and fracture strength of the mixes respectively. The addition of rejuvenators was found to significantly reduce the stiffness of the mix with high RAP content. The predicted complex shear modulus (G*) obtained from the Hirsch model and performance grading tests on extracted binders confirmed the effectiveness of the addition of rejuvenators in reducing the stiffness of recycled asphalt binder in the recycled mixes.


Worcester Polytechnic Institute

Degree Name



Civil & Environmental Engineering

Project Type


Date Accepted





RAP, Rejuvenators, MIST