Fatigue performance of asphalt pavements containing RAS and RAP.

Details

• Creators:
  Ghabchi, Rouzbeh ; Zaman, Musharraf ; Barman, Manik ; Singh, Dharamveer ; Boeck, David L.
• Corporate Creators:
  University of Oklahoma. School of Civil Engineering and Environmental Science
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Asphalt pavements
  • Reclaimed asphalt pavements
  • Recycled materials
  • Hot mix paving mixtures
  • Fatigue (Mechanics)
  • Dynamic modulus of elasticity
  • Creep
  • Pavement cracking
  • Rutting
  • Laboratory tests
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• Publication/ Report Number:
  FHWA-OK-15-01
• Resource Type:
  Tech Report
• Geographical Coverage:
  Oklahoma
• Corporate Publisher:
  Oklahoma. Dept. of Transportation. Materials and Research Division
• Abstract:
  Rising oil and gas prices spurs development of methods and technologies for reducing fuel consumption and increased use of ; recycled materials. With increased environmental awareness, using reclaimed asphalt pavement (RAP) and reclaimed asphalt ; shingles (RAS) in pavements have been gaining momentum nationally and globally. However, despite their advantages, there are ; national concerns associated with fatigue and low-temperature cracking potential of pavements when containing increased amounts ; of RAS and RAP. Therefore, this study was undertaken to evaluate the fatigue performance of hot-mix asphalt (HMA) containing ; RAS and RAP. Specifically, changes in fatigue resistance and cycles to fatigue failure with changes in the amount of RAS and RAP ; were examined using both flexural fatigue (four-point beam) and axial fatigue (cyclic direct tension) tests on laboratory compacted ; specimens. Effect of virgin binder grade on the fatigue performance was also examined. In addition, the effect of RAS and RAP in ; HMA on its creep compliance and dynamic modulus was investigated. These properties are used in the evaluation of fatigue ; resistance based on the axial cyclic direct tension test. For this purpose, eight fine surface course mixes (S4) with different types of ; asphalt binders (i.e., PG 64-22 OK and PG 70-28 OK) containing different amounts of RAS and RAP were designed and tested in ; the laboratory. The amount of RAS and RAP in HMA mixes varied, but the total amount of replaced binder was kept within certain ; specifications (i.e., RAP and/or RAS limited to 30% binder replacement). It was concluded that the fatigue life of asphalt mixes with ; a PG 64-22 OK binder increased with use of RAP or a blend of RAP and RAS. Using a blend of 5% RAP and 5% RAS in a mix led ; to the maximum increase in fatigue life. However, it was observed that the fatigue life of the mix decreased when 6% RAS was used ; compared to that of virgin mix with the same type of asphalt binder (PG 64-22). Also, it was found that when a PG 70-28 OK asphalt ; binder was used, use of RAP and/or RAS in a mix resulted in a decrease in fatigue life. Using 6% RAS resulted in the maximum ; decrease in fatigue life, compared to that of virgin mix with the same type of asphalt binder (PG 70-28 OK). Use of a polymer-modified asphalt binder (PG 70-28 OK) was found to be an effective way to increase the fatigue life of virgin mixes. More ; specifically, if RAP and/or RAS was used fatigue life was a concern. Furthermore, it was concluded that high coefficient of variation ; values of the cycles to failure found for four-point beam fatigue test show that the repeatability of this method was not very good. ; The dynamic modulus and creep compliance test results revealed that addition of RAP and/or RAS to asphalt mixes increased their ; stiffness, for cases in which PG 64-22 OK or PG 70-28 OK asphalt binders were used. This may result in a better rutting ; performance, but may lead to a mix with a higher low-temperature cracking potential versus the virgin mixes. Finally, it was found ; that indirect tensile strength (IDT) of the asphalt mixes increased with use of RAP and/or RAS compared to those of virgin mixes. ; Use of 6% RAS resulted in the maximum increase in IDT values. Also, a comprehensive survey was conducted among the state ; departments of transportation for gathering data on the current practices including the methods and specifications associated with ; the use of RAS and RAP in pavements. The results from this study can be used to develop/update guidelines/special provisions for ; design of HMA containing RAP and RAS in Oklahoma.
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• Format:
  PDF
• Funding:
  ODOT SPR Item Number 2245
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/29305/dot_29305_DS1.pdf
• File Type:
  [PDF - 4.52 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:4b03e6f233aed2feddbbdd20f49c2e76a04f7e77245df28601d0fc95308738b6