Moisture Sensitivity of Hot Mix Asphalt (HMA) Mixtures in Nebraska – Phase II

As a consequential effort to the previous NDOR research project (P-564) on moisture damage, this report presents outcomes from this project incorporated with the previous project. Performance changes and fundamental material characteristics associated with moisture damage due to various anti-stripping additives in asphalt mixtures are studied through various experimental approaches and a numerical simulation. Three additives (i.e., one reference additive, hydrated lime, and two alternative additives: fly ash and cement) are investigated by adding them into two types of mixes (SP2 for low-traffic-volume roadways and SP5 for high-traffic- volume roadways) where two different asphalt binders (PG 64-22 for the SP2 mix and PG 70-28 for the SP5) are used. Two asphalt concrete mixture scale performance tests, the AASHTO T-283 and the APA under water, and two local-scale mixture constituent tests, the boiling water test (ASTM D 3625) and the pull-off test, are conducted to characterize the effects of binder-specific anti-stripping additives on the binder-aggregate bonding potential in mixtures. The pull-off tensile strength tests are then numerically modeled through the finite element technique incorporated with the cohesive zone modeling approach to seek more fundamental scientific insights into the effect of each anti-stripping additive on the overall moisture damage resistance. Results from laboratory tests and numerical simulations indicate that the SP5 mixtures, where high-quality aggregates and polymer-modified binder are used, are fairly self-resistant to moisture damage without treating any anti-stripping additive and do not show any visible sensitivity among additives, whereas the effects of additives and their sensitivity are significant in the SP2 mixes that use the unmodified binder PG 64-22 and low-quality aggregates. With the limited amount of test data, hydrated lime seems to perform slightly better than other additives, particularly with longer moisture-conditioning time. Fly ash contributes to reducing moisture damage by improving binder-aggregate interfacial properties, which are validated from the integrated experimental-computational evaluation.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; References; Tables;
  • Pagination: 88p

Subject/Index Terms

Filing Info

  • Accession Number: 01150712
  • Record Type: Publication
  • Report/Paper Numbers: NDOR Research Project Number: MPM-04
  • Contract Numbers: 26-1107-0106-001
  • Files: NTL, TRIS, STATEDOT
  • Created Date: Feb 3 2010 3:06PM