What is the effect of adding air-entraining mixtures to concrete?

Adding air-entraining mixtures to concrete primarily improves freeze-thaw resistance, making this response correct. Air-entraining agents introduce tiny, stable air bubbles into the concrete matrix, which act as tiny shock absorbers. This provides space for water to expand upon freezing, reducing the internal pressure that can cause cracking and damage. As a result, concrete with entrained air exhibits enhanced durability in climates subject to frequent freeze-thaw cycles.

The other aspects of concrete properties are affected differently by air-entraining admixtures. For example, while they can enhance some workability due to the lubrication effect of the air bubbles, excessive air can lead to reduced compressive strength because of the lower density. Typically, they do not significantly reduce setting times and are more associated with improved performance in weather-related durability.