Identifying the Fundamental Mechanisms of Potassium Acetate Deicer on Runways

Potassium acetate (KAc) is a chemical applied to the surface of airport runways to inhibit the formation of ice (anti-icing agent) or melt ice already formed (deicing agent). It became widely used in the early 1990's after discovering the high environmental cost of glycol-based deicers. It has since become the predominant anti/deicing agent in use on runways in the USA, but has been associated with premature distress and failure of portland cement concrete at a few airports across the country. The observed distress appears to be alkali-silica reactivity (ASR) of aggregates, with map cracking visible on the pavement surface and a loss of physical integrity throughout the structure. ASR only occurs if there is "reactive" silica aggregate in the concrete, a source of hydroxyl (OH-) anions, and water present in the concrete. Reactive aggregates are amorphous, cryptocrystalline or poorly crystalline silica species such as opal or chert. Hydroxyl ions are supplied by portlandite (Ca(OH)2), a mineral compound that forms as portland cement hydrates and is therefore included in the hardened cement paste matrix. Water is supplied by the environment in which the pavement is placed. The basic chemistry of the ASR distress process is relatively well understood whereas the mechanism leading to cracking is less well understood. The first step in the chemistry of the process - the dissolution of silica - is the focus of this research. The acetate anion is a carboxylate and is known to enhance the dissolution of minerals, silica included. In fact, carboxylates are widely used in water treatment regimes to control silica deposition in process water circuits. In particular, acetate solutions are used to dissolve colloidal silica that has precipitated on the surface of process water systems.

Language

• English

Project

• Status: Active
• Funding: $8000.00
• Sponsor Organizations:

  Michigan Technological University, Houghton

  University Transportation Center for Materials in Sustainable Transportation Infrastructure (UTC-MiSTI)
  1400 Townsend Drive, 301 Dillman Hall
  Houghton, MI  United States  49931
• Project Managers:

  Hoy, Elizabeth

• Performing Organizations:

  Michigan Technological University, Houghton

  1400 Townsend Drive
  Houghton, MI  United States  49931
• Principal Investigators:

  Sutter, Lawrence

• Start Date: 20090511
• Expected Completion Date: 0
• Actual Completion Date: 0
• Source Data: RiP Project 26131

Subject/Index Terms

• TRT Terms: Aggregates; Airport runways; Alkali aggregate reactions; Deicing chemicals; Fracture mechanics; Pavement performance; Texture
• Uncontrolled Terms: Potassium acetate
• Subject Areas: Aviation; Pavements; Transportation (General); I30: Materials;

Filing Info

• Accession Number: 01461513
• Record Type: Research project
• Source Agency: University Transportation Center for Materials in Sustainable Transportation
• Files: UTC, RIP
• Created Date: Jan 3 2013 1:47PM