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snowy road at sunset

In many parts of the world, winter months bring cold weather, snow, and ice. When snow and ice cover roadways, they become slippery and unsafe to travel on. In order to prevent icy roadways, mixtures of salts are often applied. These coarse salt crystals called rock salts dissolve in snow and ice, melting ice and preventing new ice from forming.

Pure water has a freezing temperature of 0°C (32°F); as salts dissolve in water, the freezing temperature decreases, which requires colder temperatures for ice to form. The exact temperature will depend on the type of rock salt used; sodium chloride rock salt will prevent ice formation down to -9°C (15°F) while calcium chloride rock salts will prevent ice formation down to -29°C (-20°F).

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The Problem With Rock Salt

Though rock salts are effective at melting ice, issues may arise during the application onto roadways. Studies have shown that after road application from a salt truck, many of the rock salt crystals get physically displaced and end up on the shoulders of roads or off the road completely.

Another issue is the need for water to be present when applying salt. As salt reacts with water, it generates heat, which aids in melting ice. Dry salt distributed onto roadways that lack a source of moisture due to low humidity conditions during winter storms are ineffective at melting ice. An alternative deicing method is prewetting the rock salt with a salt brine solution or other prewetting agent before distribution onto the roadways.

Salt brine for roads is a mixture of rock salt and water, and can be comprised of one or a combination of different types of salts. In prewetting deicing treatments, the salt brine solution is mixed with dry rock salt as it is distributed onto the roadway. This prewetted rock salt adheres better to the roadways, resulting in higher roadway retention and more effective melting. Prewetting also reduces the amount of rock salt needed, greatly increasing efficiency and reducing salt costs.

A municipality using brine as a prewetting agent for road deicing contacted Hanna Instruments for a quick and easy solution for measuring the concentration of their salt brine for roads.

The Customer's Challenge

The customer had a batch plant in which they added water gravimetrically to sodium chloride rock salt to make a 23.3% by weight salt brine; this percentage is the most effective at preventing ice formation, with a freezing temperature of -21°C (-6°F). They were checking the concentration of each 400-gallon batch by measuring the specific gravity with a manual hydrometer, but wanted an easier and more accurate method of analysis.

An Easy and Accurate Way to Analyze Salt Brine for Roads

Hanna Instruments offered the Digital Refractometer for Measuring Sodium Chloride in Food - HI96821.


The HI96821 is easy to use, with a one-point calibration with deionized water and one-button sample measurement. The HI96821 gave the customer the option to measure their concentration in either of their preferred units of % weight (g/100g) or specific gravity. The customer appreciated the 0.1g/100g resolution, as well as the meter’s range of 0-28 g/100g encompassing their target concentration of 23.3%. Additionally, the customer appreciated the durability of the HI96821 offered by the IP65 water protection.

The HI96821 Refractometer provided a simple and accurate solution to their salt brine testing needs.

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