Evaluation of the Optimum Percentage of RAP and RAS in Asphalt Mixes in Texas Using Accelerate Pavement Testing

The first APT project at the University of Texas at Arlington took place between May 2012 and August 2015. The project, funded by the Texas Department of Transportation (TxDOT), aimed to validate the maximum allowable percentage of Recycled Asphalt Pavement (RAP) and Recycled Asphalt Shingles (RAS) allowed by TXDOT Specifications. To accomplish the validation, twelve pavement structures were built and subjected to APT loading. The experiment was a factorial combination of four asphalt surface mixes with different percentages of RAP and RAS tested for their resistance to rutting, fatigue cracking and reflection cracking. The project also aimed to validate that poor results on lab prepared asphalt mixes containing RAP and RAS translates to poor field performance under full-scale axle loads and to verify overlay design tools recently developed by Texas A&M Transportation Institute (TTI) to predict mix cracking and rutting of new asphalt overlays. The paper presents the development of the APT experiment, briefly discusses the recorded performance of the studied mixes and provides a summary of the results obtained in this experiment.