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原文传递 Developing Friction Data to Support the Optimal Use of Pre-Wet Deicing Salt for Enhanced Winter Mobility.

题名：	Developing Friction Data to Support the Optimal Use of Pre-Wet Deicing Salt for Enhanced Winter Mobility.
作者：	Akin, M.; Zhang, Y.; Shi, X.
关键词：	Deicing salts, Asphalt pavement, Snow–pavement, Best practices, Performance, Frictional behavior, Safety effects
摘要：	Applying prewet deicers during winter storms is a cost-effective strategy to improve deicer performance. Prewet deicers have a small amount of liquid product applied to solid salt or salt/sand which helps activate the ice melting and penetration and significantly reduces bounce and scatter. Prewetting keeps the product on the road and improves the ability of plows to removed compacted snow and ice. While many agencies use prewet deicers, there is not enough reliable data to determine optimal prewetting rates or product type. This research presents the results of an in-depth survey of the pacific northwest (Oregon, Washington, Alaska and Idaho) on prewetting practices and laboratory tests that quantified the ice melting, frictional behavior and reduction in snow–pavement bond strength of salt prewet with various liquid deicers and prewetting rates. Ice melting tests are an accepted method to gauge basic chemical performance, but do not adequately predict field performance. More sophisticated laboratory tests on asphalt pavement with realistic snow and representative trafficking motion and forces were conducted. Whereas ice melting tests require unrealistically high application rates (over 1000 pounds per lane mile (lb/lm)), the snow/traffic/friction tests were conducted with reasonable application rates (250 lb/lm). For the ice melting tests, pre-wetted salt worked better than dry salt at 1,000 lb/LM at 25 degrees F and 2,000 lb/LM at 15 degrees F. The biggest different observed between the types of liquid used for pre-wetting were at 25 degrees F 1,000 lb/LM tests. At the colder temperature of 15 degrees F the pre-wetting liquids worked similarly and each better than dry salt. Considering all temperatures and application rates the ranked order of liquids from best to worst are: CaCl2, Grape blend, Beet blend, 23% NaCl, MgCl2. For the snow–traffic–plowing–friction tests, pre-wetting reduced the snow–pavement bond compared to dry salt and control tests (no deicer application). The highest friction after plowing was observed with the dry salt test, although this experiment did not mimic the bounce and scatter that would be expected during application by material spreaders. The best-performing pre-wetting liquid with respect to friction was NaCl and with respect to snow–pavement bond was beet-modified salt brine. The laboratory tests confirmed that pre-wetting liquid-to-solid application rates in the range of 8–16 gal/ton are reasonable for increasing the speed and total ice melting capacity of solid salt. Furthermore, prewetting significantly reduces the snow–pavement bond, but does not seem to increase friction more than dry salt. One key limitation of the laboratory tests conducted was that bounce and scatter from realistic application speeds was not included. Thus field tests are critical for expanding the knowledge and identifying specific best practices of pre-wetting. Specific road types and data that should be collected during field operational tests are provided.
报告类型：	科技报告