Development of Hot Mix Asphalt Pavement Performance Properties for Long-life Pavement Design: Caltrans District 2, Interstate 5, Red Bluff, California

In the period 2012 to 2014, Caltrans designed and built three long-life asphalt pavement (LLAP) rehabilitation projects. Two projects were in District 2 on Interstate 5 and one was in District 4 on Interstate 80. This technical memorandum describes the processes by which performance-related test criteria were developed for a pavement section on the project on Interstate 5 just north of Red Bluff, California. The pavement section was designed and constructed as an LLAP section consisting of the following pavement components: A hot mix asphalt (HMA) surface course containing a polymer-modified asphalt (PG 64-28PM), 15 percent reclaimed asphalt pavement (RAP), and a representative aggregate from the Red Bluff area treated with 1.2 percent lime (marinated). An HMA intermediate course containing a conventional asphalt binder (PG 64-10) and the same lime-treated aggregate as the surface course plus 25 percent RAP. An HMA rich bottom layer containing conventional asphalt binder (PG 64-10) and the same lime-treated aggregate as the intermediate course, and containing 15 percent RAP Representative materials were obtained by Caltrans District 2 from the Red Bluff area for the testing to develop the design and performance-related specifications for this project. During the testing of these materials some changes were made in the mix specifications regarding the asphalt binder grade and the inclusion of RAP in the surface mix and in the rich bottom mix; these are described in this memorandum. Caltrans headquarters staff from the Office of Flexible Pavement (formerly the Division of Flexible Pavement) designed the structural pavement sections using material parameters developed from AASHTO T 320 shear testing and AASHTO T 321 fatigue and stiffness testing results. To properly establish testing protocols and parameters, it was also necessary to investigate traffic loading and environmental factors as part of the study. This testing produced the performance-related testing criteria that were included in the project specifications and bid documents. In addition to the AASHTO T 320 and T 321 results used for design and performance-related specifications, results from AASHTO T 324 Hamburg Wheel-Track Testing (HWTT) were required in the performance-based specifications as a consideration for moisture sensitivity. The HWTT results were not used in the design process.