Laboratory Evaluation of Unbound RAP as a Pavement Base Material

More than 50 million tons of asphalt pavements are milled every year in the United States (Taha 1999). The economical benefit attracts the recycling practice of utilizing RAP as paving materials.

In unbound RAP material, aged asphalt wraps aggregates. It is believed that unbound RAP performs differently from usual unbound material due to the existence of asphalt wrap. In the present study, triaxial tests were conducted for the unbound RAP under different temperatures. In addition, limestone and gravel were tested in order to compare with RAP. The resilient modulus, triaxial static creep behavior and hysteresis loops were obtained to compare the differences between the unbound RAP, limestone and gravel. The specimens were prepared at optimum moisture content and equivalent compaction work. The laboratory results indicated the RAP characteristics change with different temperature. It was found that RAP requires more compaction work than limestone and gravel. According to AASHTO 307-99, higher resilient moduli were obtained in RAP than limestone and gravel. However, larger permanent deformation was observed in RAP. Specific design consideration should be added for utilizing RAP as base material.

As part of my graduate research, finite element analysis was conducted for pile foundation over cavernous bedrock and for an Accelerated Loading Facility (ALF) in Louisiana Transportation Research Center (LTRC). The FE simulations were attached in Appendices.