List common deterioration types observed in concrete bridges.

• A. Cracking, spalling, delamination, map cracking, scaling, and corrosion of reinforcing steel.
• B. Rust staining is the only issue observed in concrete.
• C. Pitting and loss of cross-section in steel.
• D. Scaling and frost heave are the primary deterioration types.

Answer: (A)

Common deterioration types observed in concrete bridges include a mix of surface and internal damage that develops from environmental exposure and steel reinforcement reactions. Cracking is a frequent signature, arising from shrinkage, temperature changes, and loading, and it often paves the way for water, chlorides, and other deleterious agents to enter. Spalling, where surface chunks break away, can result from freeze-thaw cycling or from the pressure created by expanding corrosion products in the reinforcing steel. Delamination is an internal separation of concrete layers that may not be visible on the surface yet reduces member stiffness and load transfer. Map cracking describes a shallow, irregular crack pattern on the concrete surface that resembles a map, typically linked to restrained shrinkage and temperature effects. Scaling is the progressive flaking or shedding of the surface layer, often accelerated by deicing salts and freeze-thaw action. Corrosion of reinforcing steel is a major deterioration mechanism; as steel rusts, it expands, inducing cracks, spalling, and delamination and compromising the structural integrity of the member.

Other options don’t capture the range of common deterioration seen in concrete bridges. One option focuses only on rust staining, which is not a full description of typical damage. Another emphasizes pitting and cross‑section loss of steel, which pertains more to steel components than to concrete deterioration per se. The last option pairs scaling with frost heave, but frost heave relates to soil movement rather than concrete bridge deterioration patterns.