12.5 : コンクリート中における空気連行の効果

Air entrainment using air-entraining agents introduces tiny bubbles into concrete, enhancing durability under freeze-thaw conditions.

These bubbles create internal spaces, allowing water to expand upon freezing without causing damage to concrete.

Adding air to concrete reduces its density and strength, which poses challenges in structural applications requiring high strength.

The decrease in strength is directly proportional to the added air volume, demanding a careful balance in the mix design to maintain durability and structural integrity.

Air entrainment also enhances the ease of handling concrete by simplifying mixing, transportation, and placement.

The ease of handling is valuable in heavily reinforced structures where thorough compaction and consistent distribution are essential for durability.

The air bubbles act as internal lubricants, reducing friction within the concrete components and promoting a smoother flow.

The air-entrained concrete withstands de-icing chemicals and salt scaling, extending its lifespan and preserving its appearance.

Additionally, it reduces plastic shrinkage by evenly distributing stress as the concrete sets and dries, minimizing surface cracks.