Winter highway maintenance strategies: Are all the sodium chloride salts the same?

Abstract

Winter road maintenance is a critical function of public works and transportation agencies in states with harsh winter climate or in cold regions. The use of salts represents a cost-effective snowfighting technique, having beneficial impact on public safety, essential mobility and travel costs. Nowadays, sodium chloride (NaCl), in its three available variants (rock, solar and vacuum pan salt), is by far the most widely used chemical for snow and ice control due to its abundance and low cost. There is a worldwide large variation in the actual price of NaCl due to several factors, but often the purchase cost, at the same logistical constraints, is mostly influenced by the origin of the extracted salt and by the demand for better performance expectations. The authors decided to analyze the emblematic case of Italy, a region where supplies from salt pans or port landings are equally widespread sales channels compared to salts from underground mines. Thus, the paper evaluated some fundamental properties of different rock salts, solar sea salts and vacuum pan salt directly supplied by salt storage sites of different Italian highway agencies, which manage comparable road networks (extension and traffic volume) exposed to similar harsh winter climates, following standardized and non-conventional testing procedures related to deicing performances and to engineering characteristics (hygroscopicity, spreading behavior, caking tendency).