Photo from: Unsplash with credit to Sam Farallon
As our seasons become more dramatic and dynamic, managing snow, ice, and rain in winter can be a challenge. Using salt or sand on ice and snow will make a difference. Knowing when and where to use them is pivotal.
How Salt Works to Manage Ice Salt helps to melt ice by decreasing the freezing temperature of the water. Pure water freezes at 32 degrees F, but a 20% solution of ice drops the freezing point to almost 0 degrees F. However, to work on the ice, the salt must end up in a water solution. This can happen when sunlight, traffic friction, or heat in the pavement melts some of the ice, or by the salt attracting water from the atmosphere.
How Sand Works to Manage Ice Sand and other abrasive materials work by improving traction over ice. Friction may melt the ice, but this is an incidental addition to the functionality.
Advantages of Using Salt Salt removes the ice from the road, melting it as long as the temperature is not too low.
Disadvantages of Using Salt There is a limited temperature window in which salt can be used to de-ice roads. Below that temperature range, the ice is too cold to melt even if the salt forms a layer of brine. Even within the effective range, more salt is needed the colder it is, and the slower it will work.
Advantages of Sand Sand can be used effectively at any temperature. As long as it is spread over the ice it will provide the necessary traction.
Also, dry snow will stick to a salted ice patch while it will blow off an unsalted ice patch, meaning if the salt is applied during a storm it can cause further dangers on the road.
Disadvantages of Using Sand If the weather is too cold, the sand can clump and freeze together, becoming part of the ice and providing no traction. Adding some salt can keep this from happening.
Sand is only effective as long it is on the surface. If it is buried under more snow, it must be reapplied. Heavy traffic areas will also quickly move the sand off the road, requiring regular reapplication.
Ecological Impact of Using Salt Salt and salt water runoff contaminate the area around the road and down the drainage path. Vegetation within 60 feet of the road is damaged, and salt can contaminate ground water and wells.
Salt will also degrade steel and concrete structures. This means using salt will damage the cars on the road as well as bridge structures and even pavement. New construction techniques are minimizing this problem, but it is not yet solved.
Ecological Impact of Using Sand Sand and other abrasive materials collect on the sides of the road, in drainage ditches, and can be washed into streams and lakes. Clean up after storms is becoming a bigger and bigger concern. Particles can also be ground up and become an air pollution concern. Because sand is often combined with salt to improve effectiveness, all the environmental impacts of salt also apply to most applications of sand.
Neither sand nor salt is a perfect solution for removing ice from the roads. However, they are the best options currently available.