What phenomenon occurs when heavier dry materials in concrete settle to the bottom?

The correct concept associated with the settling of heavier dry materials in concrete is segregation. This phenomenon occurs when the different components of a concrete mix, such as coarse aggregate, fine aggregate, and cement, separate due to gravity or other forces. Segregation can lead to a material that has uneven distribution of ingredients, negatively affecting the strength and durability of the concrete.

Bleeding, while related to the movement of water in concrete, refers specifically to the process where excess water rises to the surface after the concrete has been placed. This is typically a result of the heavier solid particles settling down, but it is not the term used to describe the settling of dry materials themselves.

Curing involves maintaining the necessary moisture, temperature, and time conditions for the concrete to achieve its desired strength and durability after placement. It does not relate to the physical separation of materials.

Compacting refers to the process of removing air voids from freshly placed concrete to improve density and strength. It focuses on the consolidation of the concrete mixture rather than the separation of its components.

Understanding segregation is important for ensuring that concrete mixes maintain uniformity and perform as intended.