Which part of a bridge is particularly vulnerable to water and chloride attack, affecting longevity and durability?

• A. Abutment
• B. Bridge Deck
• C. Substructure
• D. Piers

Answer: (B)

Chloride-induced corrosion of reinforced concrete is the main durability risk, and the deck is the most exposed surface to water and chlorides. Water carries chloride ions to the steel reinforcement; when chlorides reach the steel, they disrupt the protective oxide layer and start corrosion. On the bridge deck, reinforcement is closest to the surface and faces direct exposure to rain, splash from road spray, and de-icing salts used in winter. Cracks, joints, and sometimes thinner protective cover on the deck allow chlorides to penetrate more readily, so moisture and salts linger at the top where the reinforcement is most vulnerable. As corrosion advances, the deck cover spalls and cracks, reducing durability and shortening service life. Other parts can be submerged or better protected and may receive less direct chloride exposure, so they are not as susceptible to this specific combination of exposure and reinforcement proximity as the deck.