Ionic salts as anti-icing agents have been extensively used to eliminate accumulation of ice on asphalt surfaces. However, salt can be easily removed by rain or automobiles and requires frequent application on roads. Besides this economic consideration, anti-icing agents compromise the mechanical properties of asphalt and have a negative impact on living organisms and the environment when used in large amounts. Incorporation of hydrophilic salts into bitumen, a hydrophobic asphalt binder, and controlled release of specific molecules from this hydrophobic medium can provide an effective solution for reducing ice formation on pavements.
As winter approaches, stores, cities and homeowners are stocking up on salt, gravel and sand in anticipation of slippery roads. But this annual ritual in colder climates could soon become unnecessary. Researchers report on a new road material that could de-ice itself.
Every winter, when weather forecasters predict snow or icy conditions, local governments deploy trucks that dust roads with salt, sand or other chemical mixtures to help prevent ice build-up. But the de-icer doesn’t stay on the streets for long.To break this cycle, Seda Kizilel and colleagues wanted to see if they could devise a way to ice-proof the road itself.
A new road material (right) delays the formation of ice compared to conventional materials (left). Credit: American Chemical Society
They started with salt potassium formate and combined it with the polymer styrene-butadiene-styrene. They added this mixture to bitumen, a major component of asphalt. The resulting material was just as sturdy as unmodified bitumen, and it significantly delayed ice formation in lab studies. The new composite released de-icing salt for 2 months in the lab, but the effects could last even longer when used on real roads, the researchers note. In that instance, the salt-polymer composite would be evenly embedded throughout the asphalt. Thus, as cars and trucks drive over and wear away the pavement, the salt could continually be released – potentially for years. http://www.acs.org/content/acs/en/pressroom/presspacs/2015/acs-presspac-december-16-2015/deicing-roads.html
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