Which factors influence the slump range selected for concrete in transit?

• A. Ambient temperature alone.
• B. Color of cement and batch ticket complexity.
• C. Transport method and placement method.
• D. Transport method, placement method, formwork, ambient temperature, and desired finish.

Answer: (D)

The main idea is that the slump range chosen for concrete in transit must accommodate how the concrete will be moved, placed, and finished, along with environmental and formwork needs. Transport method determines how long the concrete stays in motion and may involve pumping or chute discharge, which can cause slump loss or require sustained workability. Placement method affects how the concrete is conveyed into forms and around rebar or obstacles, influencing how fluid or stiff the mix must be to fill without segregation. Formwork characteristics, including its type, tightness, and the presence of reinforcing, set the constraints for how easily the concrete can be placed and consolidated. Ambient temperature impacts the rate of stiffening and slump loss in transit, so hotter conditions may require a higher initial slump to compensate. Desired finish guides how much workability is needed to achieve a smooth surface without tearing or excessive surface defects.

Color of cement and batch ticket complexity do not influence slump range, while focusing only on ambient temperature or on transport or placement alone misses several critical interactions.