When finishing concrete, the movement of water to the top surface is known as what?

The movement of water to the top surface of freshly poured concrete is referred to as bleeding. This phenomenon occurs as the heavier solid particles of concrete settle under the force of gravity, allowing the lighter water to rise to the surface. As water moves upward, it can create a layer on top of the concrete, which may need to be managed to ensure proper finishing and to avoid issues such as surface defects or weak layers.

This process can impact the final appearance and strength of the cured concrete, making it essential for contractors to be aware of and address bleeding during the finishing process. Properly timing finishing techniques is crucial since finishing too early, when bleeding is still occurring, can trap excess water underneath the surface and lead to problems like surface scaling or dusting.

Efflorescence refers to the white, powdery substance that can form on the surface of concrete due to the migration of soluble salts and moisture, but it does not describe the movement of water during the initial curing phase. Laitance is a similar phenomenon that involves the formation of a weak layer on the surface of concrete due to the upward migration of fine particles and water, but this is a different process than what bleeding describes. Bonding pertains to the adherence of materials together, which is not