Road salt (also called de-icing salt) usually consists of at least 94 percent (ideally 98 percent) of conventional table salt and is used in winter to melt snow and ice on traffic routes. It is, therefore, a measure of winter service, which is essentially intended to counteract slippery snow and ice. Search for liquid de-Icer for sale
Composition Of Road Salt
The commercial road salt consists mainly of table or rock salt, i.e., sodium chloride (NaCl). It can also contain minor natural minerals such as anhydrite (calcium sulphate), magnesium sulphate, or clay. Road salt is mostly only used on public roads.
Requirements For Road Salt
- Road salt NaCl
- Minimum proportion of NaCl 98%
- Grain distribution steady
- Most considerable grain content over 1.6 mm maximum 10%
- Small grain content below 0.16 mm maximum 5%
- Products with a low sulphate content are preferred
- The proportion of insoluble substances must not exceed 0.25%
- Moisture when stored in a hall maximum 1.2%
- Water in silo storage top 0.6%
The effect of road salt is related to its molar lowering of the melting point. This makes use of the fact that solutions have a lower melting point than pure liquids.
Ice and water are in a state of equilibrium between solid and liquid forms, i.e., H. there is always some liquid water available, even when the temperature is below zero. The ions of the salt dissolve immediately in this water film and form a disruptive factor that prevents a renewed “merger” into the crystalline structure of the water (ice): In the presence of salt, the water cannot freeze again; the road salt prevents the meltwater from freezing again.
But since more and more ice melts at the interface between ice and salt solution, which cannot freeze again, the ice slowly dissolves completely. In a NaCl-water ice mixture, the melting process starts at -21.1 ° C after adding salt (NaCl).
After sprinkling the ice with (enough) road salt, a solution of salt in water is created, which has a lower melting point than pure ice and remains liquid even at lower temperatures. Conventional table salt is well suited as road salt in a few minus degrees, from approx. -10 ° C other salts such as the environmentally harmless calcium chloride or magnesium chloride are more suitable.
The individual user in the small area sprinkles the salt in powder form on the icy region. Large-scale applications, especially in road traffic, are lightly mixed with brine and then applied over a wide area using a spinner attached to the vehicle. Due to its damp condition, the wind is not so well-tolerated and is restricted to the road.
To achieve the full effect on the road, however, certain framework conditions must be in place. The road temperature may only fluctuate within a specific range. If it is too deep, no thawing effect can be achieved even with salt. In addition, the road must have a particular frequency of vehicles.
Moving cars cause the ice to melt due to the increased pressure, i. H. melts more than without traffic, that the ice is crushed and that the “sludge” of salt solution and ice is thrown outwards in considerable quantities. With the repeated whirling up, water also evaporates, which concentrates the salt solution, thereby dissolving more ice. Tire-wide fairways soon form and the roads – starting from there – gradually become ice-free and dry. Click to know about liquid de-Icer for sale
Spraying processes represent a particular case. Since calcium chloride is very hygroscopic, it is best brought onto the street as a salt solution. A liquid mixture of magnesium chloride and calcium chloride with a dew point of below -30 ° was used in the GDR.