What is the maximum recommended time to place concrete after batching in typical field operations?

What is the maximum recommended time to place concrete after batching in typical field operations?

• A. Exactly two hours after batching.
• B. As specified by the project specs and the batch ticket, typically within the stated time window to avoid slump loss and premature stiffening.
• C. After the concrete has begun to stiffen.
• D. Any time within the workday.

Answer: (B)

Time from batching to placement is limited to preserve workability and prevent premature stiffening. The maximum placement time is defined by project specifications and the batch ticket, which set the valid window to place the concrete. This window accounts for factors like temperature, slump loss, and the specific mix design to ensure proper placing, compaction, and strength development. Two hours after batching is not universal; the allowable time depends on the mix and conditions. Placing after the concrete has begun to stiffen defeats proper placement and finishing, and placing any time within the workday is too vague given temperature and mix changes.

Time from batching to placement is limited to preserve workability and prevent premature stiffening. The maximum placement time is defined by project specifications and the batch ticket, which set the valid window to place the concrete. This window accounts for factors like temperature, slump loss, and the specific mix design to ensure proper placing, compaction, and strength development.

Two hours after batching is not universal; the allowable time depends on the mix and conditions. Placing after the concrete has begun to stiffen defeats proper placement and finishing, and placing any time within the workday is too vague given temperature and mix changes.