What are common causes of abnormal concrete temperature at delivery?

• A. Low ambient temperatures only.
• B. Using only cold water reduces temperature too much.
• C. Exothermic heat buildup is not a factor in transit.
• D. High ambient temperatures, excessive batch water, long transit times, or exothermic heat buildup.

Answer: (D)

Temperature at delivery is driven by heat generated inside the mix as cement hydrates and by heat exchange with the surroundings. A large mass of concrete or cementitious materials generates more heat, especially during curing, so the temperature can stay high as it travels. Hot outdoor conditions push the concrete temperature up because the surrounding air can transfer heat into the mix. The longer the transit time, the more heat has time to accumulate and less opportunity there is for cooling, which also raises the temperature you’ll see on delivery. Exothermic heat buildup is a normal part of hydration and can contribute to higher temperatures during transit, especially with larger batches or dense mixes.

Other options miss part of the picture. Focusing only on low ambient temperatures is too narrow, and blaming only cold batch water doesn’t cover the common real-world factors that can raise temperature. Saying exothermic heat isn’t a factor in transit ignores the ongoing chemical reactions that keep releasing heat after mixing. The most complete and accurate combination of causes is high ambient temperatures, excessive batch water, long transit times, and exothermic heat buildup.