DURABILITY STUDY OF VISCOSITY GRADED AC-20 ASPHALTS IN PENNSYLVANIA

This long term asphalt durability project was constructed in September 1976 using six AC-20 asphalts from different sources with the following objectives: (a) to study the changing asphalt properties on aging, (b) to determine the effect of rheological properties of asphalts on the pavement performance and durability especially at low temperatures, and (c) to develop suitable specifications for AC-20 asphalt cements to insure durable pavements. Two test pavements developed extensive low temperature non-load associated transverse cracking during the first severe winter of 1976-1977. This was attributed to high stiffness moduli of asphalts used in those pavements. A maximum permissible stiffness modulus of 275 kg/cm square (26.9 MPa) at -10F (123C) was selected to develop AC-20 asphalt specifications for the cold regions of Pennsylvania. This specification was adopted in 1977 to minimize low temperature cracking. Load associated longitudinal cracking of the pavements was attributed to low ductility values at 60F (15.6C) of the aged asphalts. It has been recommended that the minimum requirements of 15 cm ductility at 60F (15.6C) on the TFO (thin film oven) residue of the AC-20 asphalts be increased to 30 cm.

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 76 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00391347
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-PA-84-009 Final Rpt.
  • Contract Numbers: 76-12
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Jan 30 1985 12:00AM