Air entraining admixtures create air voids that do which of the following?

• A. Increase strength
• B. Decrease workability
• C. Create air voids and improve workability
• D. Increase water demand

Answer: (C)

Air voids formed by air-entraining admixtures are tiny, stable bubbles that act like lubricants inside the fresh concrete. They reduce internal friction, allowing the mix to flow and compact more easily, which improves workability. Those micro air voids also provide space to accommodate the expansion of water as it freezes, enhancing durability in freeze–thaw environments. So the best description is that these admixtures create air voids and improve workability. They don’t primarily increase strength, decrease workability, or significantly raise water demand.