When concrete is vibrated, it serves what primary purpose?

When concrete is vibrated, the primary purpose is to remove air from the mixture and increase the slump. Vibration helps to consolidate the concrete, allowing it to flow into all areas of the formwork and ensuring that it fills any gaps or voids. As the concrete vibrates, the air bubbles that may be trapped within the mixture rise to the surface, reducing the likelihood of air pockets, which can weaken the final product. This process also increases the workability of the concrete, often measured by a higher slump, resulting in a denser and more durable slab once the concrete sets and cures.

This is important because a well-formed mixture without excessive air improves the integrity of concrete, optimizing its strength and durability. In many cases, the elimination of air spaces contributes to a better bond between aggregates and the cement paste, leading to an improved overall quality of the concrete.