General Contractor Practice Exam

What is the main advantage of air entrainment in concrete?

1. Improved workability

2. Increased compressive strength

3. Enhanced freeze-thaw resistance

4. Lower cost of materials

The correct answer is: Enhanced freeze-thaw resistance

Air entrainment in concrete primarily serves to enhance freeze-thaw resistance. When air-entraining agents are added to concrete, they create tiny air bubbles within the mix. These bubbles provide space for water to expand when it freezes, reducing internal pressure and the risk of cracking as the concrete undergoes freeze-thaw cycles. This is particularly important in climates where water can freeze and thaw repeatedly, as it helps maintain the integrity and durability of the concrete over time. The incorporation of air into concrete does contribute to other benefits, but the main advantage associated with air entrainment is its ability to mitigate damage from freeze-thaw conditions, making it essential for concrete used in exterior applications or regions subject to extreme temperature fluctuations.