Improving the Properties of Reclaimed Asphalt Pavement for Roadway Base Applications.

摘要

The objective of this study was to improve Reclaimed Asphalt Pavements (RAP) strength in base course applications while reducing creep to an acceptable level using compaction techniques, fractionating, blending with high quality base course aggregate, and/or by chemical stabilization with asphalt emulsion, Portland cement, or lime. RAP/limerock blends with and without chemical stabilization were compacted by modified Proctor, Marshall, or gyratory methods, cured, and tested for strength and creep. Strength tests included limerock bearing ratio (LBR), unconfined compression, Marshall compression, and indirect tensile tests. Strength specimens were tested dry and soaked to evaluate retained strength. Seven-day onedimensional creep testing was performed. Gyratory compaction produced higher densities than modified Proctor or Marshall compaction. At the same density, gyratory compaction improved RAPs strength by a factor of two to three over modified Proctor but had less effect on creep. Modified Proctor moisture-density plots followed an S-shape without a clear optimum; modified Proctor may not be the best method to predict RAP compaction behavior. Fractionating RAP did not improve strength or creep unless RAP was remixed to match a maximum density curve. Fractionating did not produce acceptable LBRs or creep. RAP blended with limerock, cemented coquina, or reclaimed concrete aggregates showed improved LBR and creep performance. RAP/aggregate blends have the potential to be used as Florida base course. As the amount of aggregate blended with RAP increased, LBR increased and creep decreased. Creep behavior of blends with 75% aggregate was similar to 100% aggregate. Unstabilized blends with 50% aggregate did not produce LBR values over 100. Blends of 50% RAP/50% limerock stabilized with 1% of either asphalt emulsion or cement attained soaked LBRs over 100 and acceptable creep. Blends of RAP with 75% limerock attained soaked LBRs close to 100 and low creep without any chemical stabilizer. Adding RAP to limerock blends generally increased the soaked retained strength and improved permeability compared to 100% limerock.