1 / 26

Effect of Deicing and Anti-Icing Chemicals on HMA Airfield Runways

Effect of Deicing and Anti-Icing Chemicals on HMA Airfield Runways. D. Christensen, J. Mallela, D. Hein, E. Kalberer, M. Farrar, and R. Bonaquist FAA Worldwide ATT Conference, April 2010. Introduction.

merritt
Download Presentation

Effect of Deicing and Anti-Icing Chemicals on HMA Airfield Runways

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Effect of Deicing and Anti-Icing Chemicals on HMA Airfield Runways D. Christensen, J. Mallela, D. Hein, E. Kalberer, M. Farrar, and R. Bonaquist FAA Worldwide ATT Conference, April 2010

  2. Introduction • Some evidence that deicing/anti-icing chemicals (DIAICs) can cause or contribute to premature failure of HMA runways • Purpose of this presentation is to summarize recent research on effect of DIAICs on HMA airfield runways

  3. Background: Deicing vs. Anti-icing • Deicing is the removal of existing ice and/or snow from the runway • Anti-icing is application of chemicals to prevent buildup of ice and/or snow on the runway • Anti-icing is also performed on airplanes in specific locations, using similar chemicals

  4. Background: Chemicals • For aircraft deicing, ethylene and propylene glycol most commonly used • Potassium acetate most commonly used airfield pavement DIAIC • Other chemicals used include sodium acetate, potassium formate and sodium formate • Recent shift away from glycols and urea

  5. Background: Problems • In the 1990s airfields in Norway and Sweden switched from urea to potassium acetate and potassium formate • Problems later observed in HMA runways: softening, stripping, degradation, disintegration

  6. Summary of Previous Research: Scandinavia, Canada • High temperatures probably needed to cause DIAIC-related damage • Chemical mechanism not clear; DIAICs might attack asphalt-aggregate bond, and/or soften asphalt binder • Damage tends to be more severe for HMA with softer binders, higher air voids

  7. Approach in AAPTP 5-3 • Develop laboratory test and evaluate DIAIC-related damage (if any) in the laboratory • Perform airfield site visits, evaluate possible DIAIC-related damage, take specimens for testing in laboratory • Develop recommendations

  8. Lab Testing: Aggregates • Virginia diabase, 9.5-mm • Virginia Limestone, 9.5-mm • Mississippi chert/gravel, 12.5-mm • Virginia siliceous gravel, 12.5-mm • Pennsylvania greywacke sandstone, 9.5-mm

  9. Lab Testing: Binders • PG 58-28 • Two PG 64-22s • One PG 76-22, polymer modified

  10. Lab Testing: DIAICs • Propylene glycol • Sodium formate • Sodium acetate • Potassium acetate • All as 2 % solutions in water

  11. Similar to AASHTO T 283 Gyratory specimens/cores No vacuum saturation 4 days in 2 % DIAIC solution at 60 C Control: 4 days water at 60 C Tensile strength ratio Immersion/Tension (IT) Test

  12. Four Experiments with IT Test • Aggregate effects • Five aggregates • Single PG 64-22 binder • Binder effects • Three aggregates • Four different binders • Air Voids and hydrated lime effects

  13. Aggregate Effects Experiment The PA sandstone and MS chert/gravel are highly AS reactive

  14. Binder Effects Experiment This confirmed that softer binders are more susceptible to DIAIC-related damage.

  15. Air Voids/Hydrated Lime Expt.: Virginia Gravel/PG 64-22 There is possibly some slight DIAIC damage at 7 % air voids

  16. Air Voids/Hydrated Lime Effects: Mississippi Chert/PG 64-22 Lower air voids reduce DIAIC-related damage

  17. Air Voids/Hydrated Lime Expt.: Mississippi Chert/PG 58-28 In this case, HL also seems to reduce damage

  18. Other Laboratory Testing: Surface Tension and Density • As found by other researchers, DIAICs reduce the surface tension of water • DIAICs can also increase the density of water • Decreased surface tension and increased density could aggravate moisture damage

  19. Site Visits • Four airfields: Boston Logan; Colorado Springs; Boise, Idaho; and Friedman in Hailey, Idaho • Inspection of HMA damage • Photographs • Cores • Laboratory tests on cores

  20. Boston Logan

  21. Friedman Airport

  22. IT Test on Field Cores: Water and2 % Potassium Acetate Solution

  23. Conclusions • The IT test successfully demonstrated DIAIC-related damage in the laboratory for one aggregate (Mississippi chert) • Significant DIAIC-related damage was not observed in mixes made using four other aggregates and in testing of field cores using the IT test

  24. Conclusions • It appears that DIAIC-related damage is not a widespread problem in North America • DIAIC-related damage, when it does occur, appears to be an acceleration of moisture damage, and can be treated in the same way—additives, careful compaction to low/normal air voids

  25. Conclusions • The IT test appears promising, but lack of a large number of susceptible mixes made complete evaluation problematic • Additional research on the IT test would be useful, to confirm its effectiveness in identifying mixes susceptible to DIAIC-related damage

  26. Acknowledgments • Support of the AAPTP program • Monte Symons • Co-authors at ARA and WRI • Laboratory personnel

More Related