Which statement about deicing salts and steel bridges is true?

• A. They have no impact on protective coatings
• B. They accelerate corrosion of steel and deterioration of protective coatings, increasing rust risk
• C. They improve the adhesion of protective coatings
• D. They only affect concrete components

Answer: (B)

Deicing salts create a salty, conductive environment on the bridge surface, which accelerates corrosion of steel and also damages protective coatings. Chloride ions from the salt penetrate coatings and disrupt the protective oxide film on steel, allowing moisture and oxygen to reach the metal more easily. Once the coating is compromised, rust can form under and through the coating, leading to quicker coating degradation such as blistering and peeling and, in turn, more exposure of the steel to corrosion. That combination—faster steel corrosion and faster coating deterioration—drives an increased rust risk, which is why this statement is true. The other options miss the mark because salts do impact coatings, they do not improve coating adhesion, and they affect more than just concrete components.