WINTER MAINTENANCE STRATEGIES

Keeping roads open and safe in winter are the paramount concerns of highway officials. However, the cost and efficiency of snow and ice control measures are practical considerations that cannot be overlooked. To balance these needs, most winter highway deicing programs are based on the use of relatively inexpensive rock salt and/or abrasive materials. However, many departments have adopted maintenance strategies that utilize calcium chloride to enhance the effectiveness of these basic materials, reduce the volume of material required to melt ice from pavement, and prevent ice from forming on sections of roadway that can quickly become hazardous under freezing precipitation conditions.

Prewetting
Rock salt is prewet with a liquid calcium chloride, such as LIQUIDOW™ Technical Grade Calcium Chloride Solution, to enhance its ice melting efficiency. The application of liquid calcium chloride provides rock salt with the moisture it needs to more quickly begin to form liquid brine and initiate melting action, particularly at cold temperatures when dry rock salt can only dissolve very slowly. Prewetting salt and abrasives with calcium chloride also keeps the solid materials free-flowing while reducing clumping, for more uniform and cost-efficient application. Prewetting has been found to further improve deicing economics and efficiency by significantly reducing bounce and scatter loss.¹

Anti-icing
Applying ice melting chemicals before or at the start of freezing precipitation prevents the formation of bonded ice on pavement, eliminating or reducing the need for subsequent deicing applications after plowing. Use of anti-icing applications can be particularly useful on areas of roadway that quickly become hazardous to motorists as conditions deteriorate, including bridges, sharp curves, steep grades, and problem intersections. Compared to deicing after weather events, effective pre-treatments typically require less ice melter material – up to 75% less according to the U.S. EPA, reducing costs as well as potential environmental impact.²

Dry Blending
Dry blending of rock salt with solid calcium chloride can be useful in cold climates and on critical road sections such as bridges, highway ramps, and sharp turns or grades. Use of dry blends on critical sections of road can significantly reduce the time required to break the bond between ice and pavement, particularly at temperatures below 15^oF. The strongly hygroscopic calcium chloride attracts moisture and begins to melt ice even in frigid conditions when dry rock salt dissolves very slowly. As calcium chloride dissolves, heat is released, which speeds ice melting. This provides moisture needed by the dry rock salt to help it dissolve into ice melting brine.

Spot Use of Solid Deicer
Municipal and other road authorities may find the faster ice melting and colder temperature capabilities of solid calcium chloride helpful in emergency situations where there is a need to mitigate thick accumulations of ice. Application of high potency solid deicer, such as DOWFLAKE™ Xtra 83-87% Calcium Chloride Flakes, may help crews to penetrate and undercut thick ice caused by burst water mains, ice dams in drainage culverts, layers of ice at the scenes of fires, or respond to other emergency situations where delays in ice mitigation can increase the hazard, result in more damage, or impede repairs.

¹ Salt Bounce and Scatter Study, Michigan Department of Transportation, 2012
² Water Protection Practices Bulletin, United States Environmental Protection Agency, August 2010