What does "bleeding" in concrete refer to?

"Bleeding" in concrete specifically refers to the phenomenon where water rises to the surface of freshly placed concrete. This occurs as the heavier solid particles settle to the bottom of the mix, allowing the water to move upward. This can be a critical aspect to consider in concrete finishing because if excessive bleeding occurs, it can lead to problems such as surface weakness, difficulties in finishing work, or even an increase in susceptibility to cracks. It's essential for finishers to monitor and manage bleeding to ensure a durable and well-finished concrete surface.

The other options address different aspects of concrete work, but they do not accurately describe the process referred to as bleeding. For example, drying and curing processes involve the hydration and chemical reactions that solidify the concrete, while the mixing process pertains to combining the various components before pouring. The extraction of air pockets, often addressed in concrete consolidation, is distinct from the movement of water to the surface. Each of these processes play important roles in concrete finishing, but only the movement of water to the surface is defined as bleeding.