Which of the following best indicates good uniformity of concrete during discharge from a mixer truck?

• A. Observe for consistent flow, absence of segregation, consistent slump along the discharge, and no lumpiness or color change in the stream.
• B. Check only the temperature of the concrete during discharge.
• C. Rely on color matching the stream to the ticket.
• D. Rely solely on the batch ticket for acceptance.

Answer: (A)

Focusing on how the mix behaves as it leaves the truck is the best way to judge uniformity. Good uniformity is shown by a steady, cohesive flow from the mixer with no separation of components. You’d expect the slump to stay about the same along the entire length of discharge, indicating consistent workability throughout the stream. There should be no lumps forming and no color changes in the stream, because those signs point to pockets of material that aren’t uniformly mixed or are starting to segregate as the concrete pours.

Temperature, by itself, doesn’t tell you about uniformity—the concrete can be at the wrong temperature but still stay well mixed as it flows, or vice versa. Relying on color alone to judge uniformity isn’t reliable, since lighting and batch color differences can mislead you. And checking only a batch ticket ignores what’s actually happening during discharge, so you might miss real-time issues with how the mix is behaving as it’s placed.

So, the best indicator is observing the discharge for consistent flow, absence of segregation, a stable slump along the discharge, and no lumpiness or color changes in the stream. This combination shows the concrete is staying uniformly mixed as it’s delivered.