How does exterior exposure influence required concrete cover for reinforcement?

• A. Exposed environments typically require greater cover to protect steel from moisture and chlorides
• B. Exposed environments require less cover due to better ventilation
• C. Interior exposure and exterior exposure require the same cover
• D. Cover is irrelevant to exposure conditions

Answer: (A)

Exterior exposure increases the risk of moisture and chlorides reaching the reinforcement, so concrete cover must be greater to protect the steel. The concrete acts as a barrier, and increasing cover lengthens the diffusion path for water, oxygen, and chlorides, slowing corrosion initiation and progression. In less aggressive interior conditions, less cover is acceptable because the threat level is lower. Ventilation helps drying but doesn’t replace the need for adequate cover.