When concrete for a slab placement is discharged from the truck chute, how should truck arrivals be spaced?

When concrete for a slab placement is discharged from the truck chute, how should truck arrivals be spaced?

• A. 10 Min.
• B. 15 Min.
• C. 20 Min.
• D. 30 Min.

Answer: (B)

Spacing truck arrivals about 15 minutes apart keeps the slab pour flowing smoothly. This cadence gives the crew time to place, consolidate, screed, and finish the concrete while the current load is still workable, yet not so long that the concrete starts stiffening and risk cold joints. If trucks come in too quickly, the finishers can be overwhelmed and the surface quality can suffer. If they come too slowly, the concrete may begin to stiffen before finishing, making it harder to achieve a uniform, well-bonded surface.

Spacing truck arrivals about 15 minutes apart keeps the slab pour flowing smoothly. This cadence gives the crew time to place, consolidate, screed, and finish the concrete while the current load is still workable, yet not so long that the concrete starts stiffening and risk cold joints. If trucks come in too quickly, the finishers can be overwhelmed and the surface quality can suffer. If they come too slowly, the concrete may begin to stiffen before finishing, making it harder to achieve a uniform, well-bonded surface.