China has created an asphalt additive that protects roads from ice for eight years
Researchers at Hebei University in China have developed a new kind of acetate-based salt to replace chloride-based salts. The latter, although very common in nature, have an extremely negative impact on the environment. Until recently, there was no alternative to them to combat glaciation on the roads, which created a lot of problems for transport and pedestrians.
Acetate-based salts have three key advantages over chlorides. First, they lower the temperature at which ice forms. Secondly, they are less aggressive to other substances and do not cause corrosion. Thirdly, Chinese chemists have managed to create salt that does not wash out and is practically not consumed for a long time.
The secret of the new substance is that it replaces the mineral additive in asphalt, is part of it, and is not poured on the outside. To do this, the salt was mixed with sodium bicarbonate, silicon dioxide and blast furnace slag. The resulting powder was treated with a polymer and a set of capsules was obtained, which were poured into the asphalt mixture.
Capsules in a layer of asphalt 5 cm thick gradually release the active substance over a period of 7-8 years. Such material sharply reduces the temperature of ice formation: from 0ºC to -21ºC, therefore, in mild frosts, it does not form at all. All precipitation turns into liquid water and flows into the drainage system, leaving the roadbed clean.