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Copyright
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(Copyright © 1997, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing) |
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Abstract
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Frictional characteristics of sand and sand-deicer mixtures were investigated as functions of temperature, gradation, and application rate.
RESULTS of a laboratory cold-room study in which sliding friction was measured with a British pendulum tester are described. Four temperatures, three sand gradations, four brine concentrations, and four sand-application rates were investigated. All tests were performed on an ice sheet in a cold room, where sand temperatures were maintained close to ice temperatures. Three categories of materials were tested: sand alone, sand-salt mixtures, and sand-brine mixtures.
RESULTS showed that sand-brine mixtures outperformed the other two, with significantly greater sliding friction. Two brine concentrations were found suitable in two temperature ranges. Below -12°C, 2.5 percent brine (by weight) gave good results with a fine sand (passing the No. 30 U.S. sieve but retained on the No. 50 sieve) at a sand application rate of 1 g over a test area of 100 x 200 mm, with a sand-to-brine ratio of 1:1 by weight. This rate is equivalent to field application of 183 kg of sand per lane-km. Friction was achieved by generating a bond between sand and ice by using a low-concentration brine (2.5 percent by weight). At temperatures above -12°C, satisfactory results also were obtained with 25 percent brine mixed with the same sand at a ratio of 2:1 by weight. In this case, friction was increased by roughening the ice surface with a higher-concentration brine (25 percent by weight).
Language: en |