How does using too fine an aggregate affect fresh concrete?

Using too fine an aggregate can indeed lead to segregation and bleeding in fresh concrete. When the aggregate is overly fine, it tends to increase the surface area in contact with the cement paste, resulting in a higher water demand. This can disrupt the balance of the mix, causing the lighter cement particles and water to rise to the surface while the heavier aggregates settle, leading to segregation.

Additionally, this phenomenon may exacerbate bleeding, where excess water gathers at the surface of the concrete as it begins to set. This can be problematic, as the presence of water at the surface can weaken the final hardened concrete, create a weak top layer, or potentially lead to issues with finishing.

In contrast, other options suggest improvements or no significant impacts, which don't accurately reflect how too fine an aggregate affects the behavior and properties of fresh concrete during the finishing process.