The principle of using calcium chloride as a snow and ice melting agent

The principle of calcium chloride (CaCl₂) as a snow and ice melting agent mainly depends on its strong moisture absorption, heat release and lower freezing point. The specific process is as follows:
1. Strong hygroscopicity 
When calcium chloride is sprinkled on the road surface, because its strong hygroscopic property, calcium chloride can absorb moisture from surroundings and form calcium chloride solution. The calcium chloride solution can penetrate the surface of snow and ice, come into contact with it and melt it.

2. Exothermic action
The dissolution of Calcium chloride is an exothermic reaction in which a large amount of heat is released, which helps to accelerate the melting process of ice and snow.

3. Lower freezing point
The freezing point of calcium chloride solution is about -20℃, which is much lower than that of snow and ice. After mixing calcium chloride solution with snow and ice, the freezing point of snow and ice can be effectively reduced, and make it difficult to refreeze, so as to achieve the effect of melting snow and ice.

Calcium chloride snow melting agent can be manually or machine spreaded on the road. It can be sprinkled at the beginning of the snow, or estimated 1-2 hours before freezing.

The quantity of calcium chloride for snow and ice melting should be choosed according to the amount of snow:

1, When the snowfall reaches 0.1-2.4mm, the use of calcium chloride is about 100 grams/square meters.

2, when the snowfall reaches 1.3-3.7 mm, the use of calcium chloride is about 150 grams/square meter.

Advantages of calcium chloride as snow melting agent
  Wide effective range : Calcium chloride can still play a snow melting role at extremely low temperatures (below -20°C), while the snow melting effect of sodium chloride usually begins to weaken around -9°C.
  Fast dissolution speed: calcium chloride dissolution speed is fast, can quickly form high concentration solution, improve snow melting efficiency.

#Precautions
  Corrosive : Calcium chloride is corrosive to metals, concrete and other materials, and long-term use may lead to damage to roads and facilities.
  Environmental impact: Excessive use may affect the health of soil and plants, and the amount should be controlled reasonably.

In short, calcium chloride is widely used in snow removal work on roads and public places in winter because of its efficient snow melting performance.