Why is temperature control important on FDOT concrete placement projects, and which measures are commonly used on site?

• A. High heat accelerates hydration and can cause cracking; manage with scheduling, shading, misting, cooling measures and proper curing.
• B. Temperature has no impact on early strength; only slump matters.
• C. Low temperatures always improve workability and cure faster; no action needed.
• D. Temperature control is only needed to protect workers from heat.

Answer: (A)

Temperature control is essential because the heat released during cement hydration can cause the concrete to heat up rapidly, leading to nonuniform cooling and internal stresses that promote cracking and affect early strength. By keeping the concrete temperature within a controlled range, you promote uniform curing, reduce the risk of thermal cracks, and help achieve predictable early strength.

On the job, this is done through a combination of practical measures: scheduling pours for cooler parts of the day, shading fresh concrete to limit solar heating, misting or fogging to provide evaporative cooling and maintain surface moisture, and employing cooling measures such as using ice or chilled water in the mix or other cooling techniques, along with proper curing to retain moisture and support controlled hydration. This multi‑pronged approach is what effectively manages temperature and supports durable, high-quality placement.

Other statements misstate the impact of temperature on early strength or focus only on worker safety, whereas temperature directly influences concrete performance and cracking risk, not just comfort for personnel.