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Liquid anti-icing chemicals on asphalt : Friction trends Leggett, Timothy S ; Sdoutz, Gerald D

By: Leggett, Timothy SContributor(s): Sdoutz, Gerald DPublication details: Transportation Research Record, 2001Description: nr 1741, s. 104-13Subject(s): USA | Deicing | Chemistry | | Skidding resistance | Coefficient of friction | Moisture | Flexible pavement | Variability | 71Bibl.nr: VTI P8167:1741Location: Abstract: Research was done to determine whether there existed a chemical "slipperiness" on an asphalt surface as a result of a transition of typical anti-icing chemicals currently in use from a liquid to a solid state, and vice versa. The research has shown that during the state transition of most anti-icing chemicals a "slurry" phase is formed. This produces a relatively short-lived reduction in the coefficient of friction for most chemicals. At relative humidity levels in the high 20s to low 30s, most chemicals begin to dry out after application as a liquid, causing the state transition. Humidity values above those required to cause the state transition appear not to affect the friction dramatically. All chemicals, upon continued dehydration, reached a solid state. The solid state coefficient of friction of most chemicals is essentially equivalent to that of a clean and dry asphalt roadway. Some even increased the coefficient of friction above 1.0. It appears that prudent use of the chemicals, particularly with regard to application rate, frequency, and other contaminants, while bearing in mind expected humidity levels, can further reduce the likelihood of slickness developing, particularly in the fall season when most incidents are reported. It is believed that most anti-icing agent-related incidents are probably a result of the chemical being applied after a dry period, which likely causes a slippery emulsion to be formed by the chemical and the contaminants that have built up on the roadway.
Item type: Reports, conferences, monographs
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Research was done to determine whether there existed a chemical "slipperiness" on an asphalt surface as a result of a transition of typical anti-icing chemicals currently in use from a liquid to a solid state, and vice versa. The research has shown that during the state transition of most anti-icing chemicals a "slurry" phase is formed. This produces a relatively short-lived reduction in the coefficient of friction for most chemicals. At relative humidity levels in the high 20s to low 30s, most chemicals begin to dry out after application as a liquid, causing the state transition. Humidity values above those required to cause the state transition appear not to affect the friction dramatically. All chemicals, upon continued dehydration, reached a solid state. The solid state coefficient of friction of most chemicals is essentially equivalent to that of a clean and dry asphalt roadway. Some even increased the coefficient of friction above 1.0. It appears that prudent use of the chemicals, particularly with regard to application rate, frequency, and other contaminants, while bearing in mind expected humidity levels, can further reduce the likelihood of slickness developing, particularly in the fall season when most incidents are reported. It is believed that most anti-icing agent-related incidents are probably a result of the chemical being applied after a dry period, which likely causes a slippery emulsion to be formed by the chemical and the contaminants that have built up on the roadway.

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