Bleeding in concrete is caused by water rising to the surface. How can bleeding be controlled?

• A. Water rising to the surface.
• B. Controlled by mix design, placement methods, and curing.
• C. Bleeding is caused by excessive vibration.
• D. Bleeding is prevented by using larger aggregates.

Answer: (B)

Bleeding happens when water in the plastic concrete migrates to the surface, leaving behind a paste-rich layer. The amount of bleeding you get is shaped by the mix’s water content and how the solids are arranged, along with how the concrete is placed, consolidated, and cured.

Control comes from managing three things together. First, the mix design: use the right water-cement ratio, well-graded aggregates, and adequate cementitious material; admixtures like plasticizers can maintain workability without adding extra water. Second, placement methods: avoid excessive segregation during placing and consolidation, and finish the surface appropriately to minimize water movement. Third, curing: keep moisture and temperature conditions favorable to hydration, reducing rapid surface drying that can accentuate bleeding.

Putting these together is why this approach is effective. Simply focusing on one factor—like vibration or using larger aggregates—doesn’t address all the causes of bleeding and won’t reliably control it.