What is the purpose of using air-entrained concrete?

Air-entrained concrete is specifically designed to incorporate tiny air bubbles into the concrete mixture. These air bubbles serve a critical function in enhancing the durability of concrete, particularly in environments subject to freeze-thaw cycles. When water in concrete freezes, it expands, and if there is insufficient space for this expansion, it can lead to cracking and damage. The air bubbles act as "pressure relief" spaces, allowing the expanding ice to push into these voids, thereby reducing internal stress and preventing damage to the concrete.

In addition to improving freeze-thaw resistance, air-entrained concrete also benefits workability and can influence water absorption, but its primary and most important function in cold climates is to provide protection against the deleterious effects of freeze-thaw cycles.