What may occur if concrete does not have adequate air entrainment?

When concrete lacks adequate air entrainment, it becomes more susceptible to freeze-thaw damage. Air entrainment involves intentionally incorporating tiny air bubbles within the concrete mix, which serve as stress relievers when the water within the concrete freezes and expands. Without these air pockets, the concrete does not have the necessary flexibility to accommodate this expansion, leading to cracking, spalling, or other forms of deterioration when exposed to repeated freeze-thaw cycles.

The other options—improved workability in hot weather, enhanced bonding with steel reinforcement, and reduction in water absorption rates—do not accurately represent the consequences of insufficient air entrainment. Insufficient air could negatively impact workability, hinder bonding, and possibly lead to higher water absorption rates due to denser concrete that lacks small air voids. Hence, the correct identification of increased susceptibility to freeze-thaw damage highlights the critical role of air entrainment in maintaining the durability and longevity of concrete in varying environmental conditions.