Importance of Fine Aggregates in Achieving Adequate Skid Resistance in TxDOT Hot Mix Asphalt Mixtures

Details

• Creators:
  Khan, M. Aamish H. ; Omole, Adegboyega ; Reddy, G. Sandeep ; Montoya, Miguel ; Abdallah, Imad ; Nazarian, Soheil
• Corporate Creators:
  University of Texas at El Paso. Center for Transportation Infrastructure Systems
• Corporate Contributors:
  Texas Department of Transportation. Research and Technology Implementation Office ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  • Skid resistance
  • Asphalt mixtures
  • Friction
  • Testing
  • Fine aggregates
  • Hot mix asphalt
  • Laboratory tests
  • Rutting
  • Cracking
  • Moisture damage
  More +
• Publication/ Report Number:
  FHWA/TX-27/0-7108-1 ; R1B
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Edition:
  Final Report: Aug 2021 - Aug 2026
• Corporate Publisher:
  University of Texas at El Paso. Center for Transportation Infrastructure Systems
• Description:
  Skid resistance is a critical roadway-safety characteristic, but it is not routinely evaluated during asphalt mixture design. TxDOT Project 0-7108 evaluated practical methods for improving the long-term frictional performance of hot-mix asphalt mixtures, particularly mixtures containing aggregates with relatively low polishing resistance. The experimental program examined material-related factors (binder grade and aggregate type), mixture-design factors (binder content, aggregate gradation, mixture type, and the distribution of aggregate types within individual gradation fractions), and a construction-related factor (air-void content). Laboratory specimens were polished with the Three-Wheel Polishing Device (TWPD), and friction was measured with the Dynamic Friction Tester (DFT). Field sections and producer mixture designs were also evaluated, and the modified mixtures were checked for rutting, cracking, and moisture-damage performance. Within the materials and ranges evaluated, aggregate type had the dominant effect on long-term friction, whereas binder grade, binder content, overall gradation, mixture type, and air-void content had comparatively small effects after the binder film was removed. Fraction-specific testing showed that the intermediate aggregate fraction-passing the No. 4 sieve and retained on the No. 30 sieve (4.75-0.60 mm)-was especially important. The No. 4-to-No. 16 subfraction (4.75-1.18 mm)provided the largest contribution, while replacing only the material passing the No. 30 sieve provided little benefit. Targeted replacement of low-friction aggregate in the critical fraction improved terminal DFT friction while limiting the quantity of premium aggregate required. Producer case studies increased terminal DFV from 0.21 to 0.28 for an SP-C mixture and from 0.25 to 0.32 for an SMA-D mixture without compromising the evaluated mechanical performance. The proposed laboratory friction levels and the approximately 0.30 terminal-DFV screening value should be considered provisional until they are correlated with field friction and validated through implementation projects.
• Format:
  PDF
• Funding:
  0-7108
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/94035/dot_94035_DS1.pdf
• File Type:
  [PDF - 3.63 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:885250d2ea76b6dc46c5c655c63d6771106a70aa13098b4e9593bc719b43d15fbe590e8d15165d6c5f86550b79d2b599762b3a22ed7ff7517d87e245a903af73