Why Use Deicers Over Abrasives?
If you aren’t familiar with the use of deicing chemicals, you could be missing out on an efficient snow- and ice-management tool.
The reliance of our society on daily mobility and the urgency of moving emergency vehicles demands efficient snow and ice removal. According to the U.S. Department of Transportation, motorists now travel more than 2 trillion miles per year. Of people who commute, about 71 percent use automobiles. As for intra-city travel, about 81 percent is by automobile, and trucks alone move millions of pounds of goods each day.
The use of deicers is one way to help meet the demand of public pressure for clean, safe streets, parking lots and sidewalks. Deicers help provide results that abrasives cannot.
Deicers vs. abrasives
The term deicer refers to all products commonly used today in winter operations that lower the freezing point of water. The Washington State Department of Transportation (WSDOT) uses deicer chemicals because deicers are an efficient tool during winter operations. Additionally, their use increases service levels and commonly is less expensive than alternative operations.
WSDOT also uses abrasives such as sand or cinders to improve skid resistance on icy roads when temperatures are lower than the effective temperature for using deicing chemicals. Admittedly, some areas of the country have proposed the exclusive use of abrasives to eliminate the use of deicers. Cities or counties and others often make these decisions while considering only purchase price. All too often, they forget to take into consideration the total cost, safety benefits and environmental concerns associated with all types of winter operations. Failure to consider the true cost of not using an alternative, such as a deicer, many times leads to the wrong conclusion. Yet, many reasons exist why the use of abrasives alone is not normally practical or feasible (see boxed information, “Why abrasives often aren’t the answer,” page 18).
Deicer chemicals should be part of your snow- and ice-control program, whether it is for reasons of safety, economy, reduced environmental impact or to keep roadways open. You can use them in several ways, and—as much as possible—you should use all of them. The four common methods of deicer use are anti-icing, deicing, pre-wetting and stockpile maintenance.
Anti-icing. This technique is the timely application of a deicer chemical to reduce or eliminate the bond of snow and ice to the roadway surface. Anti-icing is proactive: getting ahead of the storm and working from the bottom up. Applying a deicer chemical in the liquid form is most efficient because, if you apply it correctly, you’ll lose minimal—if any—chemical from traffic. You also can use solid deicer products, but normally you pre-wet the product with a liquid deicer to reduce the material removed by traffic. Anti-icing is an excellent tool, and its proper use has shown a positive impact on service levels and overall safety of roadways and parking lots. It also provides positive benefits to operation budgets and the environment due to reduced chemical use.
Deicing. Deicing is the application of a chemical to the top of existing compacted snow or ice. This operation is reactionary, reduces service levels and often costs much more than being proactive.
Pre-wetting. This technique is the application of a liquid deicer product to a dry material prior to its application to the roadway surface. Pre-wetting abrasives—used to improve traction—helps the abrasive stay on the road and results in fewer repeat applications, which means lower material, equipment, labor and clean-up costs. You also use liquids to pre-wet dry deicer chemicals. The result is faster action of the dry material when applied, reduced material loss from traffic and, potentially, fewer re-applications. You use pre-wet dry deicer materials for both deicing and anti-icing operations.
Stockpile maintenance. This involves mixing a deicer into an abrasives stockpile to keep the abrasives workable at lower temperatures, eliminating frozen clumps of material. Mixing a deicer into abrasive stockpiles reduces labor and equipment charges because you don’t end up spending excessive amounts of employee and equipment time fighting the frozen material. With some deicer products, the amount of chemical you need to keep the stockpile workable is minimal, giving you maximum return on your investment.
Deicers do have limitations…
Many reasons exist to support the use of deicers as effective and efficient tools for winter operations. However, because they are a tool, you must understand three important things about them:
- Know when to use a deicer—and when not to use it. Consider whether to use a liquid, solid or pre-wetted solid for the current or predicted weather conditions. Often, the most effective, efficient mix results from using the various forms of deicers (liquids and solids) at the correct time or repeating applications in the anti-icing mode of operation.
- Know what to expect of the tool you’re using. Deicers are not a panacea to all your snow- and ice-management problems. And, like all tools, they have their limitations. Use them with reasonable expectations, and learn from each application. Skill and success with the use of any tool or combinations of tools comes from experience.
- Know when to put this tool away. When a deicer is not the appropriate tool to use, put it away. Don’t use the wrong tool at the wrong time or in the wrong way—with unreasonable expectations—and then blame the tool for the results you obtain.
The proper use of deicers has many advantages. Chemical deicers expedite or sometimes eliminate the need for plowing compact ice and snow by preventing or breaking the bond between ice and snow and the pavement. The chemicals accomplish this at a temperature much lower than when you don’t use a deicer. This results in safer roads at a lower overall cost.
Dale Keep is maintenance-methods specialist at the Washington State Department of Transportation. He spoke on the use of deicing chemicals at the Snow & Ice Management Association’s annual Snow & Ice Symposium last spring in Pittsburgh. He will present a half-day seminar on the topic at the 1999 symposium.
WHY ABRASIVES OFTEN AREN’T THE ANSWER
- Abrasives provide traction but do not assist in melting or removing snow and ice.
- Traffic quickly blows abrasives off the roadway. Therefore, you must reapply them often, increasing application, material and cleanup costs.
- The cleanup and disposal of abrasives is a costly operation, especially for cities that consider the material to be a hazardous waste.
- Abrasives quickly generate dust and contribute to air-quality issues.
- Abrasives alone may result in uneven driving surfaces.
- Abrasives fill and block catch basins, culverts and—in urban areas—storm sewers.
- Abrasives have an environmental impact (causing silt buildup and impeding flow) on water through the movement of the material into the waterways.
- Abrasives often require the addition of deicer chemicals anyway to keep the material from freezing, even in covered unheated storage.
- Abrasives—due to broken windshields, rock chips, etc.—are the basis for many tort claims resulting in many dollars being spent in their processing and payment.
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