Which of the following is a typical reason for surface scaling on exterior concrete?

• A. Poor curing practices.
• B. Freeze-thaw damage, salt exposure, or poor surface preparation.
• C. High early-age strength development.
• D. Proper air entrainment.

Answer: (B)

Surface scaling happens when the outer concrete layer loses cohesion and flakes away, which is most common on exterior concrete exposed to moisture and cold. The combination of freeze-thaw damage, salt exposure, and poor surface preparation explains it clearly: water in the surface pores freezes and expands, pushing the top layer apart; de-icing salts can crystallize and worsen the damage; and if the surface isn’t properly prepared (laitance, contaminants, or inadequate finishing), the top layer bonds poorly and scales off. The other options don’t fit as well: high early-age strength isn’t a typical cause of scaling, and proper air entrainment actually helps prevent scaling. Poor curing can contribute to surface flaws, but it isn’t the primary typical cause listed here.