Which method is used for consolidating concrete with a slump lower than 1 inch?

Vibration is the preferred method for consolidating concrete with a slump lower than 1 inch because it effectively eliminates air pockets and ensures that the mix flows evenly into the forms, achieving a dense and uniform product. When the slump is low, it indicates that the concrete is stiff and may be more resistant to flow, making it more challenging to consolidate through traditional methods. Vibration helps to facilitate the movement of the particles within the concrete by introducing energy that causes the mix to settle and compact, resulting in improved strength and durability once cured.

In contrast, methods like rodding are typically used with mixes that are more workable, where it can help to ensure distribution but may not be sufficient for stiffer mixes. Mixing primarily pertains to preparing the concrete rather than consolidating it after placement, and bringing does not pertain to a recognized method of consolidation. Therefore, vibration stands out as the most effective technique for this specific scenario of low slump concrete.