Concrete from a ready mix truck must be completely discharged within how many hours after water has been added at the plant?

Concrete from a ready mix truck must be completely discharged within how many hours after water has been added at the plant?

• A. 1
• B. 1.5
• C. 2
• D. 2.5

Answer: (B)

Concrete should be discharged within one and a half hours after water is added to the batch. This window helps ensure the mix stays workable long enough to place and finish, but not so long that the concrete stiffens, loses slump, and becomes hard to pump or finish. After water is added, hydration begins and the concrete gradually stiffens; staying within this time frame preserves the designed workability, air content, and overall performance. Going beyond this limit increases the risk of poor finish, segregation or bleeding, excessive heat build-up, and reduced strength or durability.

Concrete should be discharged within one and a half hours after water is added to the batch. This window helps ensure the mix stays workable long enough to place and finish, but not so long that the concrete stiffens, loses slump, and becomes hard to pump or finish. After water is added, hydration begins and the concrete gradually stiffens; staying within this time frame preserves the designed workability, air content, and overall performance. Going beyond this limit increases the risk of poor finish, segregation or bleeding, excessive heat build-up, and reduced strength or durability.