Salt vs. Sand for Winter Road Safety
Understanding the pros and the cons of salt and sand on winter road safety is important as many are trying to reduce salt usage and sand is often used as a replacement.
Sand is the original winter maintenance material. Sand is the first material that was used to help increase the friction of icy road surfaces in the winter. In recent decades, though, sand has largely been replaced by chemical deicers like sodium chloride and magnesium chloride. Chemical deicers have been found to be a lot more effective at restoring roads to safe friction levels after a snowstorm than sand. However, sand is still used for winter maintenance and there are instances where sand still makes sense.
The first thing to consider about sand and abrasives is that they have no ice melting capacity. They will not function as either deicers or anti-icers in the conventional sense. That is, they are not going to actually remove snow or ice from the road. What they can do is give you a temporary increase in road friction on iced pavements. Sand can help reduce slippery roads and ultimately reduce accidents just like removing the ice and snow. Sand can get us to where we want to be, it is just a question of which tool is the most appropriate for the given conditions.
If you want to use sand, there are a few caveats that you should bear in mind. The first one is that dry sand is not effective. The reason for its ineffectiveness is that there have been numerous studies that have shown dry sand is very easily blown off the road by moderate amounts of traffic action. If you are going to use sand, you should use wetted sand. You should pre-wet the sand with water or with a deicing liquid. Wetting the sand will help protect it from being knocked off by traffic action. Studies have shown that pre-wetting sand will enable you to reduce your sanding application rate by as much as 50%.
Sand is not environmentally innocuous. There is no such thing as an environmentally perfect material or chemical, as all materials have their own characteristic environmental impact. From an environmental friendly scale perspective, sand is better than deicing chemical. You should use sand whenever you possibly can to avoid the effects of deicing chemicals. Your ultimate environmental strategy should always be to identify the particular chemical, which can be used in the smallest amount, which works best for specific conditions.
Sand will impact air quality. Sand contributes to PM10 levels. PM10 refers to very tiny particles. These particles can form as sand is crushed by traffic action. They are tiny particles that are smaller than about 10 micron in size. They are small enough that they can remain suspended in the air and can have detrimental effects on air quality.
The use of sand will cause buildup of sediment and turbidity in waterways impacting aquatic ecosystems negatively. There have been studies by ecological experts that have concluded that the detrimental environmental effects of sand generally outweigh those of ice melting chemicals.
This doesn’t mean that we should never use sand. It simply means that we should use sand when it is appropriate, specifically, if the temperature is so cold that regular deicing chemicals won't melt the ice. Sand can provide temporary friction until the temperature warms up enough that the deicers start to work. Another instance where sand can work is if you have strongly bonded hard pack of ice or snow on the road that plows can't remove. In that case, sanding is a good option until the plows are able to come through and remove the compacted snow and ice.