Which factors should be considered before discharging concrete into forms to minimize settlement defects?

Which factors should be considered before discharging concrete into forms to minimize settlement defects?

• A. Fresh concrete properties (slump, temperature, air content), formwork condition, and consolidation method
• B. Weather forecast and daylight
• C. The truck's route and traffic
• D. The color of the concrete

Answer: (A)

Filling quality depends on controlling fresh concrete properties, formwork condition, and consolidation method before discharging into the forms. Fresh concrete properties like slump, temperature, and air content determine how well the mix will flow into corners and around reinforcement, avoid excessive segregation, and settle uniformly. If the workability is off or the temperature causes too rapid or too slow stiffening, settlement defects and voids can form as the concrete changes from fluid to solid. Formwork must be sound and properly prepared—aligned, clean, and adequately braced with tight joints and sealed surfaces. Any gaps, leaks, or misalignment can allow concrete to move unevenly or escape, creating voids or irregular settlement as the mix hardens. The consolidation method should match the section’s complexity and reinforcement, ensuring proper vibration and compaction to eliminate entrapped air and fill all voids. Inadequate or inappropriate consolidation leaves weak pockets that settle over time or exhibit honeycombing. Other options don’t directly govern placement quality—weather or daylight can influence temperature indirectly but aren’t the specific pre-discharge controls, and the truck route, traffic, or color of the concrete don’t affect the likelihood of settlement defects.

Filling quality depends on controlling fresh concrete properties, formwork condition, and consolidation method before discharging into the forms. Fresh concrete properties like slump, temperature, and air content determine how well the mix will flow into corners and around reinforcement, avoid excessive segregation, and settle uniformly. If the workability is off or the temperature causes too rapid or too slow stiffening, settlement defects and voids can form as the concrete changes from fluid to solid.

Formwork must be sound and properly prepared—aligned, clean, and adequately braced with tight joints and sealed surfaces. Any gaps, leaks, or misalignment can allow concrete to move unevenly or escape, creating voids or irregular settlement as the mix hardens.

The consolidation method should match the section’s complexity and reinforcement, ensuring proper vibration and compaction to eliminate entrapped air and fill all voids. Inadequate or inappropriate consolidation leaves weak pockets that settle over time or exhibit honeycombing.

Other options don’t directly govern placement quality—weather or daylight can influence temperature indirectly but aren’t the specific pre-discharge controls, and the truck route, traffic, or color of the concrete don’t affect the likelihood of settlement defects.