Disadvantages of rock salt as thawing salt

On average, rock salt is 20% cheaper to acquire than evaporated salt. However, this lower price is considerably outweighed by the significant disadvantages for people, the environment, the road, winter maintenance equipment and the resulting subsequent costs.

More particulate matter released into the atmosphere

It has been shown in practice that rock salt has a higher proportion of insoluble substances than de-icing salt. With an annual demand of 400,000 tonnes of de-icing salt in Austria, these insoluble residues would imply additional dust pollution of 4,800 and 13,500 tonnes.

Road safety not guaranteed

Continuous road safety cannot be guaranteed. The insoluble residues in rock salt can leave a slippery film on roads and paths. They can also bind to the rotary disc and interrupt the salt output. Unfortunately, this often goes unnoticed, or is only noticed too late, by the driver.

Asphalt pores clogged

The residues can clog up the pores of porous asphalt, meaning that the drainage of rainwater and the absorption of rolling noises no longer work ideally.

Concrete surfaces are destroyed

The sulphate content of rock salt brine is often above the threshold of 600 grams per litre of brine. Such highly concentrated sulphate can cause the concrete matrix to break apart.

Sulphate content does not comply with concrete standard

The substance that makes up the concrete mix mainly used in Austria, XA1, suffers considerably from 200 – 600 mg sulphate per litre. At -5°C, rock salt already reaches 200 mg / litre. De-icing salt, on the other hand, never reaches a critical value. Added to this is the fact that ÖNORM B 4710 includes an obligation of investment protection. According to this, the use of rock salt in winter service cannot be recommended with the requirements of ÖNORM B 4710.

Demand, transport and infrastructure costs rise

With dry spreading, the demand for rock salt is around 30% higher, while for pre-wetted salt spreading FS 30, it is around 5 – 10% higher than evaporated salt. On top of this, it also implies greater transport costs, more storage capacities, more personnel expenses, higher machine abrasion due to the higher sulphate content, more rust damage and faster wear and tear of the entire infrastructure.