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TECHNOLOG Y E: )c nw Attachment C LTAPI ,f the Minnesota I cal7echnical Assistance o Pro9mm Atyy.�4l.ntar ITY OF MINNESOTA TRARapoerrA1WN S] css Fall Expo: keeping motorists safe on winter roads Snowy, slushy, or icy pavement: more than - --- 1,300 people are killed and more than 116,800 people are injured on it each year in vehicle crashes, according to Federal Highway Administration (FHWA) reports. These num- bers would be even higher without effective snow removal and road deicing operations. But as vital as these functions are, they can eati up a big chunk of state and local agency main- tenance budgets. Researchers at Minnesota State University, Mankato (MSU Mankato) are studying various types and blends of deicing chemicals, which are typically used in combi- nation with plowing, to see which ones offer the best performance for the money. Stephen J. Druschel, P.E., assistant professor of environmental engineering, is leading this effort and was on hand at the 2011 Minnesota Fall Maintenance Expo to discuss some pre- liminary findings. "Essentially, were looking at how much snow and ice a particular chemi- cal or blend melts and how much it costs ... we All kinds of equipment were on display at the Fell Maintenance want to find out what [product] gives us the most bang for the buck,° Druschel explained. Deicers are expensive, so knowing which products to use, how much to use, and when to use them is crucial to controlling winter road maintenance costs, he continued. One of the chemical deicers they are studying is sodium chloride, more commonly known as rock salt. Rock salt is currently the most popular chemi- cal deicer because it is reliable, relatively inexpen- sive, and easy to store and apply. But because salt has been linked to causing vehicle and infrastruc- ture corrosion as well as environmental damage, Druschel's group is also evaluating some of the alternative deicers that have cropped up in response to concerns around salt use. These options include calcium magnesium acetate, calcium chloride, mag- nesium chloride, and carbohydrate solutions like beet juice and corn molasses that are generated as byproducts of agricultural operations. While these deicing alternatives are generally less corrosive and less harmful to the environment than salt, they tend to be significantly more expensive. Corrosion and environmental benefits aside, one question researchers hope to answer is whether or not the performance benefits of alternative deicers are worth the added cost. "We have evaluated more than 1,200 samples including 20 or more base prod- ucts and 30 different product blends. One of the main things we've looked at is the ice melt capacity of each product; that is, how much ice melts com- pared to how much material is used;' Druschel said. In one set of experiments, for example, they tested a salt brine base mixed first with 10 percent magne- sium chloride, then 20 percent, and finally 30 per- cent to find out what, if any, benefit there is to using ,T—A SKOJOBI as12 more of the magnesium additive. They conducted the same test using calcium chloride and carbohy- drate solutions, again mixed into salt brine at 10, 20, and 30 percent. "These [chemicals] were tested all at once so we could get a good stable temperature . for comparison; he explained. "We tested generally in the 15 to 25 degree Fahrenheit range... and while we see some benefit [to adding alternative deicers to salt brine], we found that doubling the amount doeset get you more for the money. Basically, a little [additive] helps, but more is a waste and does not provide additional performance benefit" In other tests, Druschel's team found rock salt to have the best ice melt capacity at 28 and 20 degrees Fahrenheit, with some of the alternative deicers blended with a rock salt base to be nearly as good — some even a little better. At around 12 degrees Fahrenheit, magnesium chloride actually has a 50 percent better ice melt capacity than rock salt, but most other deicers perform worse than salt at the colder temperatures. However, these alternative deicers may provide other advantages not related to ice melt capacity. For instance, many of the carbohy- drate solutions are sticky, which prevents the deicing treatment from blowing off the road before it has a chance to work. Some deicing blends, because of their color, are more visible on the road than salt alone, allowing deicing truck drivers to see where treatment already has been laid down. This helps avoid reapplying chemicals too soon —and that can produce savings anywhere from 10 to 20 percent a clay. Still, Druschel explained, ice melt capacity is the cornerstone factor that influences everything else when deciding which deicing chemicals to use. "Considering that ice melt capacity is the most 007 I r y • ` + Rock salt probably offers the best performance for the money, accord- ing to the research team. important aspect... when all is said and done, when we hold the temperature even, when the ice is con- sistent ... the amount of difference were seeing [in ice melt capacity] between rock salt and other treat- ments is minimal - -10 percent, maybe 40 preen'. at the very best; he said. So even though many salt alternatives promise to "burn up the road, this research suggests thats not quite the case. In fact, Druschel said, "Even with all these other cool products available, rock salt probably offers tine best performance for the money and is generally still, the most favorable choice" The details of this research will be presented in a final report due out in spring 2012. Coinciding with this project, Druschel's team is developing a cost performance model that can be used to calculate the base cost of deicing chemicals from the loading terminal. Users can then factor in mileage and fuel costs and calculate performance variables as well. This tool is currently in testing and is scheduled for release in the spring. —Nancy Strege, LTAP freelancer