The function of snow melting agent is to melt snow and ice, reducing the amount of material at the water point. Mainly used as a material for snow and ice removal in urban roads, highways, airports, ports, bridges and other facilities, some snow melting agents can also be used as quick solvents and antifreeze additives for winter construction of construction projects。

Snow melting agents are divided into chloride salts, such as magnesium chloride flakes in hexahydrate magnesium chloride, calcium chloride particles in dihydrate calcium chloride, sodium chloride, etc., which are called chloride salts and can be used directly or in combination (with added corrosion inhibitors). Another type is organic snow melting agents such as calcium magnesium acetate, known as acetate based snow melting agents such as calcium magnesium acetate (calcium magnesium acetate salt). The difference between the two lies in the advantage of the former being that there are more manufacturers, it is easier to find, and the price is lower. The disadvantage is that if the usage cannot be controlled, although the snow melting effect is fast, it will cause certain corrosion to vegetation, buildings, etc. Therefore, adding corrosion inhibitors to composite snow melting agents can reduce the corrosion effect. The advantage of the latter is that it is non corrosive and suitable for airports and places with high environmental protection requirements, but the disadvantage is that the price is too high.

The composition of composite snow melting agents is mainly composed of magnesium chloride, calcium chloride, and sodium chloride added to corrosion inhibitors in a certain proportion, with a general ratio of 4:3:2:1 or different ratios as required, mainly based on the non freezing temperature and snow melting efficiency.

The snow melting principle of "chloride salt" snow melting agents is that after being dissolved in water (snow), the freezing point of "chloride salt" snow melting agents is zero degrees. For example, after sodium chloride snow melting agent (the main component of table salt) is dissolved in water, the freezing point is -10 ℃, calcium chloride is about -20 ℃, and acetic acid is about -30 ℃. The freezing point of saltwater is lower than that of water, so it is difficult to form ice after dissolving salt in snowwater. In addition, after the snow melting agent dissolves in water, the ion concentration in the water increases, reducing the liquid vapor pressure of water, but the solid vapor pressure of ice remains unchanged. In order to achieve the solid-liquid vapor pressure and other states of the ice water mixture, the ice melts. This principle can also explain the reason why saltwater is not easily frozen. In short, snow melting agents lower the melting point of snow, making it easier to melt. We know that water is a special substance, that is, its density decreases after freezing (the density of a solid substance is generally greater than that of a liquid), so the higher the pressure, the lower the melting point of ice. It is natural for snow to melt easily in areas where the wheels have run over. After sprinkling snow melting agent on snowy roads, it is easy for vehicles to melt the snow. In summary, the snow melting principle of chloride based snow melting agents is that after chloride based snow melting agents dissolve in water (snow), they reduce the vapor pressure of water and lower its melting point. When studying pressure, the melting point is low and ice and snow are prone to melting. The snow accumulation caused by the use of snow melting agents often accumulates in the green belts and fields on both sides of the road. After spring, salt residues accumulate on the fields and green belts, causing crops and trees to be afraid of salt, resulting in a large number of deaths and even destruction of green plants. Even if it is replanted, all the soil must be replaced, and the fields are even more difficult to escape, and the losses are self-evident. Due to the fact that the land in the north usually contains salt, the plants in the north can resist salt and alkali, and even so cannot withstand the harm of snow melting agents. In addition, plants in acid loving soil in the south cannot withstand the harm of salt and alkali. In order to reduce the corrosion damage caused by chloride salts, for municipal infrastructure construction, one is to use high-performance concrete to improve its permeability resistance. The second is to use corrosion-resistant steel bars as much as possible, or use rust inhibitors on the steel bars. The third is to apply anti-seepage outer coatings on the exterior of buildings. The solution to plant protection is to choose salt tolerant plants along roads close to snow melting agents, and to use snow season shading methods for trees and greenery to prevent snow melting agents from coming into contact with plants. 

Based on the above statement, although the price of chloride based snow melting agents is low, if the amount used is not controlled, the side effects will be significant. Calcium magnesium acetate can compensate for the shortcomings of ordinary snow melting.