Impact of Not Using Air Entrainment in Concrete in Freezing Climates

If concrete is placed in a climate with freezing temperatures and air entrainment is not included in the mix, water inside the concrete can freeze, expand, and fracture the concrete. This damage significantly reduces the concrete's durability and lifespan.

Without air entrainment, concrete exposed to freezing temperatures in cold weather climates will fracture and deteriorate due to water expansion during freeze-thaw cycles, significantly shortening its lifespan.

Without air entrainment in concrete exposed to freezing temperatures, water within the concrete's pores can expand when it freezes, leading to fracturing and damage. This process, known as freeze-thaw damage, significantly reduces the concrete's durability and can cause it to spall or crack over time.

Why Air Entrainment is Crucial for Cold Climates

Air entrainment introduces microscopic air bubbles into the concrete mix. These tiny voids act as pressure relief valves for freezing water. When water in the concrete freezes and expands, it moves into these empty spaces instead of exerting pressure on the concrete itself, preventing internal stress and cracking. This feature was discovered to give concrete frost resistance in 1938.

For concrete subject to moderate or severe weathering, such as surfaces exposed to freezing and thawing, it must be air-entrained. For example, concrete exposed to a freezing and thawing environment should have a minimum total air content of 5 percent.

Air Entrainment in Southern California

While Southern California generally enjoys a mild climate, specific areas, especially in the mountains or high desert regions, do experience freezing temperatures and frost. For driveways and exterior flatwork in climates where the concrete might be exposed to deicing chemicals or frequent freeze-thaw cycles, an air content of 5% to 7% is typically recommended.

If you're pouring concrete in an area that regularly sees freezing conditions, an air-entrained mix is a smart investment in the longevity of your concrete. However, for concrete that is not exposed to the weather, like basement walls or interior foundations, a minimum compressive strength of 2500 psi is often specified, and air entrainment may not be required.

How Air Entrainment Affects Concrete Properties

Air-entraining admixtures are a type of chemical admixture intentionally added to concrete to entrain air. While air entrainment improves freeze-thaw resistance, it can slightly reduce the concrete's compressive strength. To counteract this, a higher specified compressive strength, such as 4000 psi, might be recommended for air-entrained concrete in severe exposure conditions, especially for surfaces like garage floors with a steel-troweled finish where air content might be reduced.

> Pro Tip: Ready-mix batch plants prefer to add air-entraining admixtures as part of the batch process rather than using pre-mixed cements, allowing for better control over the exact air content for your project's specific needs.

Properly specified and mixed concrete, including appropriate air entrainment for the climate, contributes significantly to its overall durability and resistance to weathering. You can learn more about how mix elements influence performance in our article on Water-Cement Ratio: Its Impact on Concrete Slab Durability and Performance or explore other factors in Beyond PSI: Factors Influencing Concrete Strength in SoCal Projects.

Common Mistakes

• Underestimating local weather: Assuming Southern California is universally warm, leading to skipping air entrainment in colder microclimates.
• Using non-air-entrained concrete for exterior pours: Applying standard interior slab mixes for outdoor patios or driveways exposed to winter conditions.
• Not checking mix specifications: Failing to confirm with your ready-mix supplier that the concrete is air-entrained when needed.

To ensure your concrete project in Southern California is specified correctly for its exposure conditions and intended use, carefully review the mix design with your contractor. Western Concrete can guide you through the appropriate concrete specifications for your home's unique location and project requirements.