Salt, commonly used to de-ice roads in winter, primarily affects roads by causing corrosion of their structural components.
The Corrosive Impact of Salt
When salt (specifically, the chlorides within it) is applied to roads and bridges, it initiates a chemical process that damages the materials they are made from. According to the provided reference, Chlorides corrode metal and concrete. This means that elements like steel rebar used to reinforce concrete within roads and bridges, as well as the concrete itself, are susceptible to degradation from salt exposure.
- Damage to Concrete: Salt can cause the concrete to crack and spall (break apart in layers). This occurs through various mechanisms, including the formation of expansive salt crystals within pores and the acceleration of freeze-thaw cycles when mixed with water.
- Corrosion of Metal: Steel embedded within concrete, essential for structural integrity, rusts when exposed to chlorides and moisture. As steel rusts, it expands, exerting pressure on the surrounding concrete, leading to further cracking and deterioration.
Consequences for Road Infrastructure
The corrosive effects of salt have significant negative consequences for the lifespan and maintenance of road infrastructure.
- Reduced Lifespan: Because salting often damages roads, bridges, and vehicles, excess chlorides directly reduce the lifespan of infrastructure. The continuous exposure to corrosive agents weakens the structure over time.
- Increased Maintenance Costs: The damage caused by salt necessitates more frequent and extensive repairs. Therefore, excess chlorides increase maintenance costs associated with patching potholes, resurfacing roads, and repairing or replacing bridge components.
Salt application is a necessary measure for ensuring safety during icy conditions, but it comes at a significant cost to the physical integrity and longevity of our transportation infrastructure.
