Comparison of Pelletized Lime with Other Anti-Stripping Additives

Stripping is a common problem in hot mix asphalt (HMA) pavements in Oregon, especially in Eastern Oregon. Stripping is the degradation of the bond between the aggregate and the asphalt binder due to the presence of water – this mechanism of degradation can lead to loss of capacity and cracking in the pavement. A common additive used in the industry to mitigate stripping damage is powdered lime. However, challenges with air-borne powdered lime have state highway agencies (SHAs) investigating alternatives to powdered lime. The purpose of this study was to determine the effectiveness of potential alternatives to powdered lime additive in preventing stripping. This research evaluated the moisture susceptibility of five anti-stripping additives with three separate aggregates. The aggregates exhibited a range of potential stripping from not susceptible to susceptible. Results indicate that Aggregates 1 and 3 are likely susceptible to stripping, with Aggregate 3 likely being the most susceptible. Powdered lime increased the tensile strength ratio (TSR) and environmental conditioning system (ECS) ratios for the susceptible aggregates. Mixtures with Additive 4 exhibited similar performance to mixes containing powdered lime. Additive 2 exhibited improved performance compared to the control but TSR and ECS ratios were lower than the specimens with powdered lime. Results from mixtures with Additive 3 exhibited limited improvements in TSR and ECS ratios. Additives 4 and 2 should be considered for future use in HMA when stripping could be an issue. One practice in Oregon Department of Transportation (ODOT) is to inlay HMA pavements 15 years after construction. If the pavement is exhibiting damage resulting from stripping, the inlay can be specified to be 4 inches (102 mm) deep. If the pavement is not exhibiting damage from stripping, the inlay can be specified at 2 inches (51 mm) deep. Using this information, an economic analysis was performed. Other options are available but these were not included in the analysis. The economic analysis indicates that when a reduction in inlay thickness is realized, there is significant value in using additives. The sensitivity analyses indicated that large changes in the input variables do not make the cost of using additive cost ineffective – that is, there is significant value in using additives even when input variables (rate of return, number of future inlays, inlay depth, cost of inlay HMA, original construction cost, and additive cost) change significantly.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 70p

Subject/Index Terms

Filing Info

  • Accession Number: 01529410
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-OR-RD-14-14, 0-732
  • Contract Numbers: SPR 732
  • Files: TRIS, ATRI, USDOT, STATEDOT
  • Created Date: Jun 18 2014 1:07PM