What factors contribute to slump loss during transit?

• A. Time in transit, concrete temperature, agitation from the mixer, and any delays or idle time.
• B. Ambient color, driver mood, truck color, and lane position
• C. Weather forecast only
• D. Subgrade type and location

Answer: (A)

Slump loss in transit is driven by conditions inside the mixer as the concrete sits on the way to the job site. The longer the time in transit, the more the cement paste continues to hydrate and stiffen, so the concrete loses workability. Temperature matters because higher concrete temperature accelerates hydration, causing the slump to drop faster; cooler temperatures slow that process, but still, the initial temperature is a key factor. Agitation from the mixer has a direct effect too: while rotation keeps the mix moving, it can promote water separation, paste rearrangement, and potential segregation of aggregates, all of which reduce slump. Any delays or idle time also contribute because the mix sits longer with ongoing hydration and without effective mixing, further diminishing workability.

The other factors listed don’t directly affect slump in transit. Ambient color, driver mood, truck color, and lane position have no impact on the concrete’s workability. A weather forecast by itself doesn’t capture the actual conditions inside the drum, and subgrade type or location isn’t relevant to the slump of concrete while it’s being transported.