Performance Rating of De-Icing Chemicals for Winter Operations Chris Tuan, Ph.D., P.E. Barbara Gerbino-Bevins, Civil Engineer Mike Mattison, P.E.
Objectives• Research and develop standardized tests to analyze the performance of chemical deicers• Correlate laboratory data with field data• Research and develop best practices regarding the use of chemical deicers
Overview• Literature Survey• Shaker Test – Procedure – Results• Field Data Collection – Road Condition Rating System – MDSS and AVL Data• Best Practices
Literature Survey• Chemical Deicers – NaCl, MgCl2, CaCl2 , Potassium Acetate, “Beet Juice” – Liquids and Solids• Practices – De-icing: Reactive – Anti-icing: Proactive – Prewet Solids
Literature Survey• SHRP Handbook of Test Methods for Evaluating Chemical Deicers – SHRP Ice Melting Capacity Test: Does not correlate well with field data – Resulting roadway friction after treatment – Ice penetration and Ice debonding – Thermal Properties• Research Sponsored by Clear Roads and Northwest Pacific Snowfighters
Shaker Test Thermocouple Martini Shaker 1-mL Ice Cube Tray Freezer
Shaker Test: Conclusions• Test Results – Low Variance for Each Temperature Group – K Ace Reacts with Road Salt – How Beet Juice Works• The Shaker Test – Quick, Simple, Inexpensive – Repeatable – Produces Consistent Results for Liquids and Solids at 20°F, 10°F, and 0°F
Field Data Collection• Maintenance Decision Support System (MDSS) – Web-based software – Records Vehicle Location – Weather Data• Automatic Vehicle Location (AVL) – Time Stamps of Plow Truck Locations – Records Data about Chemical Application – Takes Pictures from the Cab
Field Data Collection• Maintenance Decision Support System (MDSS) – Weather Data
Field Data Collection• Maintenance Decision Support System (MDSS) – Records and time stamps vehicle location
Road Condition RatingSystem• Based on what can be seen from the truck – Lines and wheel tracks • 100% Covered – Cannot see roadway • 75% Covered – Can see some roadway – Cannot see two defined, continuous wheel tracks or any lines.
Road Condition RatingSystem• 50% Covered – Can see two defined, continuous wheel tracks – Cannot see lines• 25% Covered – Can see two or more wheel tracks – Can see one or more lines• 0% Covered – Can see inner and outer lines – Little or no snow is on roadway
Best Practices Liquids• Best used at temperatures greater than 20°F• Pencil nozzles work well for post-treatment of ice or compacted snow layers greater than ¼ inch.• Best choice for anti-icing• Can be used during events with precipitation rates less than 0.5 in/hr• Retreat every 1½ to 2 hours to prevent refreeze Solids• Can use at temperatures as low as 12°F• Works well for post-treatment of ice and compacted snow• Smaller gradations tend to work faster, but also refreeze quicker• Coarse grained deicers can be used during events with precipitation rates greater than 0.5 in/hr
Best Practices• Not recommended to use deicers or abrasives if wind speed is greater than 15 mph• Abrasives with a pre-wet are much more effective than dry abrasives• MgCl2 and CaCl2 work better than NaCl at temperatures lower than 20°F, but can cause slippery roads if humidity is higher than 40%.• Beet juice works well in direct sunlight
Conclusions• Shaker Test can be used to screen new deicers or compare the performance of different deicers• Field Data Collection – Processing MDSS and AVL Data is Time Consuming – Provides Useful Snow Events Information for Correlation Study – More Data Required for Statistical Significance
Acknowledgments• NDOR Technical Advisory Committee: – Jasmine Dondlinger, Jodi Gibson, Lieska Halsey, Wally Heyen, Dalyce Ronnau, Amy Starr, and Gary Story.• District Maintenance Managers: – Ray Branstiter, Dale Butler, Kelly Doyle, Chris Ford, Allen Horak, Roger Klasna, and Roger Kalkwarf.• City of Omaha Public Works: – Scott McIntyre.