On concrete delivery time, how long do you have before concrete should be poured?

On concrete delivery time, how long do you have before concrete should be poured?

• A. 2 hours
• B. 1 hour
• C. 2.5 hours
• D. 1.5 hours

Answer: (D)

Concrete has a limited usable period after mixing, as workability fades and hydration begins toward setting. The standard guideline is to place the concrete within about ninety minutes (1.5 hours) of batching or discharge from the plant. This window helps ensure proper slump, placement, and compaction; going beyond it can lead to stiffening, segregation, and weak joints. Weather and admixtures affect the timing: hot weather or rapid setting shorten the window, while cold weather or the use of retarders can extend it. So the recommended time before pouring is about 1.5 hours.

Concrete has a limited usable period after mixing, as workability fades and hydration begins toward setting. The standard guideline is to place the concrete within about ninety minutes (1.5 hours) of batching or discharge from the plant. This window helps ensure proper slump, placement, and compaction; going beyond it can lead to stiffening, segregation, and weak joints. Weather and admixtures affect the timing: hot weather or rapid setting shorten the window, while cold weather or the use of retarders can extend it. So the recommended time before pouring is about 1.5 hours.