Evaluation of RAP impact on hot-mix asphalt design and performance

Hasan Ozer, Imad L. Al-Qadi, Samuel H. Carpenter, Qazi Aurangzeb, Geoffrey L. Roberts, James Trepanier

Research output: Contribution to journalConference articlepeer-review

17 Scopus citations

Abstract

This study investigates the reclaimed asphalt pavement (RAP) effect on hot-mix asphalt (HMA) volumetric and mechanical properties. An experimental program, including tests for measuring mixture complex moduli and fracture energy, was conducted. Six different mixture designs were prepared with varying percentages of RAP material (0, 20, and 40%) and two different material sources from Illinois. Because RAP binder is believed to be the only factor contributing to stiffness changes in the mixtures, it is essential to determine RAP's binder contribution; in other words "working RAP binder," which affects the HMA stiffness and the mixing/compaction process. Control specimens and actual practice specimens were also prepared to serve as reference mixes. Control specimens included RAP materials (binder and aggregate) recovered using the Rotovapor method and virgin materials. Control specimens were designed to simulate the presence of varying proportions of working RAP binder in a RAP mixture. Actual practice specimens were a combination of RAP and virgin materials (binder and aggregate). A complex modulus test was conducted on HMA to quantify the impact of the change in binder stiffness. The study found that the optimum job mix formula (JMF) asphalt content of the virgin HMA and HMA containing RAP is similar. The current assumption of 100% working binder does not need to be modified from a mix design point of view. The effect of aggregate selective absorption of binder on virgin and RAP materials was manifested in the results of the complex modulus tests. In addition, fracture energy tests were conducted to investigate the impact of RAP materials on HMA susceptibility to low-temperature cracking. The study concluded that using RAP materials may increase the potential for low-temperature cracking.

Original languageEnglish (US)
Pages (from-to)317-348
Number of pages32
JournalAsphalt Paving Technology: Association of Asphalt Paving Technologists-Proceedings of the Technical Sessions
Volume78
StatePublished - 2009
Externally publishedYes
EventAsphalt Paving Technology 2009, AAPT - Minneapolis, MN, United States
Duration: Mar 15 2009Mar 18 2009

Keywords

  • Complex modulus
  • Fracture energy
  • RAP

ASJC Scopus subject areas

  • Civil and Structural Engineering

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