Air entrainment in concrete significantly enhances the material's durability, especially in environments subjected to freeze-thaw cycles. Introducing small air bubbles into the concrete mix acts as internal voids that accommodate the expansion of water when it freezes, thereby alleviating internal stress and preventing structural cracks. This function is crucial in climates with significant freezing and thawing, as it protects the concrete from repeated stresses that could lead to premature deterioration.
While air entrainment substantially benefits concrete's durability, it also reduces the density and strength of the material. This reduction poses challenges in structural applications where high strength is of importance. The concrete mix design should strike an optimal balance between durability and the necessary structural integrity, adjusting the concrete formulation to ensure sufficient air content to enhance frost resistance and handling characteristics without compromising load-bearing capacity.
Additionally, air entrainment improves the workability of concrete. The air bubbles act as internal lubricants, reducing internal friction and facilitating easier mixing, transportation, and placement, which is particularly advantageous in constructions with heavy reinforcement where achieving thorough compaction is essential. Air-entrained concrete also offers better resistance against deicing chemicals and salt scaling and minimizes plastic shrinkage cracking during curing. It maintains both the aesthetic appearance and structural integrity over time.
