In exterior slabs, when would the minimum cover for reinforcing steel exceed 2 inches?

• A. Larger bars or harsher exposure.
• B. Softer exposure.
• C. When using smaller bars.
• D. Under normal conditions.

Answer: (A)

The amount of concrete cover over reinforcing steel in exterior slabs is increased to protect the steel from moisture, chlorides, and freeze‑thaw/damaging exposure. Using larger diameter bars means more steel surface is exposed and more concrete is needed to shield it, while harsher exposure (such as aggressive environments, deicing salts, or marine conditions) accelerates deterioration and also calls for a thicker protective layer. Therefore, when you’re using larger bars or you’re dealing with a harsher exposure, the minimum cover goes beyond the basic 2 inches. In softer exposure, with smaller bars, or under normal conditions, the minimum can stay at 2 inches.