A very good recipe of concrete in the high-performance category is not only cement, water, and sand. Brilliantly successful projects or simply failed projects have been founded on the basis of one mere chemical decision. The decision on this is whether or not to add small air bubbles to the mixture.

It is important that a project manager understands the distinction between Air Entrained Concrete and Normal Concrete. Such an option has the effect of influencing the long term durability particularly in adverse weather. In this post, we will deconstruct the disparities, advantages, and disadvantages of each to enable you to make a good decision.

What Is the Difference? A Snapshot

At its core, the difference lies in the tiny holes or voids inside the hardened material.

• Normal Concrete: This mix contains entrapped air. These are large, accidental pockets that form during mixing. They usually make up only 1% to 2% of the slab.
• Air Entrained Concrete: This mix contains millions of microscopic bubbles. Specialists create these by adding a specific chemical agent. These tiny bubbles are spread evenly and make up 4% to 8% of the concrete.

1. Fighting the Freeze-Thaw Cycle

The biggest benefit of air entrained concrete is its ability to survive freezing weather. When water inside concrete freezes, it expands by about 9%. This expansion creates massive pressure inside a normal concrete slab.

In normal concrete, this pressure causes the surface to flake off or crack deeply. However, in air entrained concrete, the microscopic bubbles act as miniature expansion chambers. They provide a relief valve for the ice to push into, which prevents the concrete from shattering. If your project faces temperatures below freezing, you must use air entrainment.

2. Easier Flow and Placement

Seasoned employees understand that air entrained concrete is not the same when you hold a shovel. The minute air bubbles are microscopic ball bearings which lubricate the whole mix.

• Easier Movement: The bubbles assist in passing the concrete through pumps and into the forms.
• Less Water Bleeding: The bubbles hold solid particles up and prevent them from sinking too fast. This keeps water from pooling on top.
• Better Finishing: While the mix moves easily, it can be a bit sticky. Finishers must time their work carefully to avoid trapping moisture under the surface.

3. The Strength Trade-Off

In construction, every benefit usually has a cost. The main drawback of adding air is a drop in overall strength.

Pro Rule of Thumb: For every 1% increase in air, the concrete loses about 5% to 6% of its compressive strength.

Because of this, you should use normal concrete for heavy-duty interior columns where freezing is not an issue. For outdoor slabs, engineers usually fix this strength loss by adding more cement or using less water in the recipe.

4. Keeping Chemicals Out

Air entrained concrete is much better at blocking liquids. Normal concrete has long, thin channels that act like straws, pulling water and salt deep inside. The microscopic bubbles in air entrained concrete break these straws apart.

This blockage makes it harder for road salt or seawater to rot the concrete from the inside out. Consequently, it is the best choice for bridges, docks, and industrial floors.

Which One Should You Choose?

Your choice depends almost entirely on the location of the pour.

• Choose Normal Concrete for indoor projects or climate-controlled warehouses. It is the best fit for high-strength structures that stay dry and warm.
• Choose Air Entrained Concrete for any outdoor surface. This includes driveways, sidewalks, and walls. It is a lifesaver in cold climates or near the ocean.

One Last Professional Tip

Always test your air levels on the job site using a pressure meter. Air levels can change based on temperature or how long the truck spent driving. When working with BATTU, accurate air levels are critical to ensure the best strength and durability. Do not leave the life of your building to chance.