Investigation on Mix Design of Recycled Asphalt Pavement (RAP) Materials

Details

• Creators:
  Le, Jia-Liang ; Marasteanu, Mihai ; Turos, Mugurel ; Zhao, Zifeng ; Khanal, Shambhavi
• Corporate Creators:
  University of Minnesota. Department of Civil, Environmental, and Geo-Engineering. Minnesota Traffic Observatory ; Local Road Research Board
• Corporate Contributors:
  Minnesota. Department of Transportation. Office of Research & Innovation
• Subject/TRT Terms:
  Asphalt Mixtures Compactibility Graphite Literature Reviews Low Temperature Tests Mix Design Reclaimed Asphalt Pavements Recycled Materials
• Publication/ Report Number:
  MN 2026-21
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Minnesota
• Edition:
  Final Report
• Corporate Publisher:
  Minnesota. Department of Transportation. Office of Research & Innovation
• Abstract:
  Recycled asphalt pavement (RAP) is widely used in asphalt mixture production because it reduces material cost, conserves natural resources, and improves sustainability in pavement construction. However, increasing RAP content can also introduce compactability issues and weak cracking resistance. For this reason, a better understanding of RAP material characteristics and mixture behavior is needed to support reliable mixture design and implementation. This project investigates the mix design, compaction behavior, and low-temperature mechanical performance of RAP mixtures, with additional evaluation of graphite nanoplatelet (GNP) modification. The work includes a literature review on RAP compaction and design, followed by RAP characterization using processed black and white curves, chunk index, gradation, moisture content, and binder content. A gradation-based mix design procedure is developed to prepare mixtures containing 25%, 40%, and 50% RAP. Gyratory compaction testing shows that, under the laboratory conditions used in this study, mixtures with higher RAP contents reach the target air void level with fewer gyrations. Additional testing shows that adding 6% GNP by weight of fresh binder moderately improves compaction and reduces gyration demand, although the benefit becomes limited at lower compaction temperature. Low-temperature semi-circular bend and bending beam rheometer tests indicate that RAP mixtures had fracture energy comparable to the virgin mixture and generally higher apparent fracture toughness and flexural strength. Overall, the results indicate that RAP mixtures designed and prepared under the conditions used in this study can achieve satisfactory compactability and low-temperature performance, supporting the feasibility of using higher RAP contents in asphalt mixtures.
• Format:
  PDF
• Funding:
  (c)1036342 (wo) 82
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:3de3b04f8f3207bff11083f59054318107a54f2ca273b4508c4d26fbf9257d6874fd1f446f60e30de0d54891a8b5144b478fc7cb347070f85dbcc888414cb896
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/92366/dot_92366_DS1.pdf
• File Type:
  [PDF - 3.08 MB ]