Now that we are looking back on a long, tough winter, many are asking questions of themselves and others concerning what they could have done differently amid salt supply challenges so they would have fared better. One question that calls for further examination is: “Can I treat sand with deicers (liquids and/or solids) for more effectiveness?” During the season, many contractors were either using a sand-salt mix, using just sand, or using pretreated sand, much like they would pretreat salt. The answer to the effectiveness question depends on the goal in mind and how it is done.
Goal 1: Melting ice
The melting capacity or performance of the deicer applied is not increased by adding sand. Sand does not melt ice. The only way to melt ice is to use a deicer chemical that lowers the freeze point of water, and in the right quantity for the existing surface temperature and the amount of ice on the road surface. If used correctly and within their specific limitations, deicers will either melt ice or keep the liquid wet at temperatures well below the normal freeze point of water. Specifically, if “X” pounds of melting capacity are needed to deal with the ice present, that is what is needed. Adding sand or any other type of grit does not change that, but adding deicer does.
Adding a deicer to sand as a solid increases the volume of material on hand but does not change the amount of deicer applied or the associated melting capacity. Sand does not melt ice, but it helps with traction, typically for a short time since it moves due to traffic action. When temperatures rise or more deicer applications are made, the inadequate amount of deicer initially applied with the sand will help melting, but the initial reduced application rate and melting capacity will not do the job at the time it is applied.
Scenario example. Imagine a situation where the correct application rate is 1,000 pounds of salt spread evenly on a property to melt the snow and/or ice present and to keep the brine created from the melting in a liquid state to enable drying. But since there’s only 500 pounds of salt on hand, it is mixed by volume in a one-to-one ratio with sand. There is now a volume of material equal to 1,000 pounds of salt, but in terms of deicer applied it is half of what is needed.
In this scenario, the ice wasn’t melted (so you wasted precious materials) and there is now the cost of the sand to consider (purchase, application, cleanup and disposal).
A better solution. When faced with a situation where ice cannot be removed, a better approach is to talk to the customer. Explain why you temporarily can’t melt the ice, and why using sand as a temporary traction control action is better than doing nothing or incorrectly using the limited deicer on hand. Assure them that as soon as circumstances allow the ice will be removed. When forced to use sand, explain why you are not able to melt the ice and why this is the best approach under the circumstances. Then apply the sand correctly, saving material and costs.
Goal 2: Manage coefficient of friction
In this situation, the goal is to provide friction/traction until circumstances change and you can melt the ice. Changes can come from temperatures rising, obtaining more deicer, or a combination. Bear in mind that the warmer it is the greater the melting capacity of every pound of deicer applied. When it warms up, 500 pounds or less could do the job.
Scenario example. When the goal is to create traction, the deicer is used to create a short-lived, thin layer of liquid with sand on top of the ice. When the liquid freezes, as it will due to the minimal amount of deicer used, it helps hold the sand in place. This reduces material movement and can reduce the need for repeat applications. With this goal, using 500 pounds of deicer is a waste of product resulting in increased costs, and it is also counterproductive. Using too much deicer can embed the sand too deep into the ice surface, diminishing the friction results desired while adding to costs and wasting deicer inventory.
A better solution. The best way to do an application where sand is used is to pre-wet the sand with a liquid deicer as it is applied. Put just enough liquid deicer on the sand to melt a small amount of ice under the grit, creating a thin layer of moisture that refreezes quickly to help hold the sand or grit in place. In this situation, the use of as little as 25 pounds of active ingredients or less, depending on temperatures and the liquid deicer being used, could do the job. Remember the goal of this application is traction rather than melting.
Adding a deicer to sand (ideally as a liquid) is not used for melting but to create temporary traction. The goal is to create just enough to melt, refreeze and hold the grit material applied to reduce loss of material and to buy time by providing traction. When sand or grit is pre-wet, it helps to reduce material loss from bounce and scatter during the application process, but it also helps hold it in place after, generally reducing the need for repeat applications. When the conditions and/or deicer inventory are right, the ice is removed.
No room for waste
Both melting and the application of sand to ice are valid approaches under the right conditions and circumstances. However, the goal of the application must be considered up front, and then approached properly in order to be effective and efficient. When a mixture of salt and sand is used without thought to the required goal, something is almost always wasted. This approach is less effective and efficient than using a mix properly designed for the goal at hand.
- If salt is in short supply, make sure you communicate with your client and explain service options, which may include delaying service if necessary.
- Before mixing sand and salt, consider your end goal and the associated additional costs (including postseason cleanup). Mixing the two to stretch supply will result in a waste of product and unsuccessful results.
- Pre-wetting sand with a liquid deicer can be beneficial if applied correctly.
Dale Keep owns Ice & Snow Technologies, a training and consulting company based in
Walla Walla, WA.