Air-entrained concrete primarily improves performance by resisting what condition?

• A. Accelerated curing
• B. Higher compressive strength
• C. Resisting freeze-thaw cycles
• D. Lower permeability

Answer: (C)

Air-entrained concrete uses additives to create many tiny, evenly distributed air voids in the paste. These microscopic pockets act as relief spaces for water that expands when it freezes. By giving the water somewhere to go, the internal pressure in the concrete is greatly reduced, which prevents cracks and spalling that would normally result from repeated freeze–thaw cycles. That’s why this type of concrete is especially valued in climates where freezing temperatures are common. It’s not about curing speed or boosting strength—in fact, those air voids can slightly reduce strength—and while they can influence how water moves through the concrete, the main benefit people seek is better resistance to freeze–thaw damage.