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Graduate Defense: Amanda Mullins

March 10 @ 10:30 am - 11:30 am MST

Thesis Defense

Thesis Information

Title: Analysis of High Recycled Asphalt Pavement Mix Design with Rejuvenators

Program: Master of Science in Civil Engineering

Advisor: Dr. Yang Lu, Civil Engineering

Committee Members: Dr. Nick Hudyma, Civil Engineering, Dr. Dave Zhai, Civil Engineering, and Alejandro Rosales, M.S., Civil Engineering


Recycled Asphalt Pavement (RAP) inclusive mixes are becoming more widely used due to the environmental and economical benefits that are associated with replacing virgin material with recycled material. However, when including a high amount of RAP replacement (more than 25%), the longevity of the mixture, specifically the cracking and rutting resistance, is negatively impacted. The incorporation of rejuvenators into these high RAP mixes is used to revitalize and restore pavement characteristics. This study evaluated the performance of two rejuvenators (RAs: Bio-based and Petroleum Based) and the ability to restore mix properties for RAP mixes at 25%, 50%, and 70% replacement. The properties of the mixes were evaluated based on balanced mix design (BMD) concepts to balance rutting and cracking resistances via the Hamburg Wheel Tracking Test (HWTT) and Indirect Tensile Asphalt Cracking Test (IDEAL-CT). The mix design process maintains a consistent aggregate gradation and asphalt content to minimize the influence of these variables. The evaluation of these mixes will consist of three points of analysis; rheological characteristics of binder blends, performance testing, and chemical assessment. A Fourier transform infrared (FTIR) was used to compare the chemical structures of the blended asphalts for different treatments. The properties from the virgin (0% RAP) mix were used as the baseline to evaluate the effects of different RAP contents and different rejuvenator effects. The outcome of this research resulted in an improved method of high RAP mix design, a comparison of two rejuvenator performances, and a three-tier method of testing to best evaluate the mix performance.