Why should bleed water be checked before finishing a slab?

• A. It can cause laitance and surface blemishes if excessive
• B. It has no effect
• C. It strengthens the surface
• D. It reduces bond with finishing materials

Answer: (A)

Bleed water rises to the surface as the concrete hydrates, and it carries cement fines with it. If you finish while this water is still on the surface, the fine cement paste forms a weak, skimpy layer known as laitance. That laitance shows up as surface blemishes, dusting, and a poor base for any topping or sealer, and it can weaken bonding of finishes. By checking for and removing bleed water before finishing, you prevent forming that weak surface layer and end up with a smoother, stronger, more durable slab that bonds properly with finishes.