How should you measure the temperature of fresh concrete on arrival at the site?

• A. Insert a calibrated thermometer into the concrete at the point of discharge or in a representative sample and record the reading
• B. Use a non-contact infrared thermometer on the surface
• C. Guess based on ambient temperature
• D. Check the truck's gauge

Answer: (A)

Measuring the temperature of fresh concrete on arrival should give a true, representative reading of the mix as it will be placed. The most reliable method is to insert a calibrated thermometer directly into the concrete at the point of discharge or into a representative portion of the batch and record that reading. This captures the actual temperature of the mixture, which matters for strength development, workability, and setting time, and it reflects the temperature inside the drum or during placement rather than just the surface.

Relying on a non-contact infrared thermometer on the surface can mislead you because surface temperature is influenced by sun, wind, cooling from the surface, or surface moisture and may not reflect the concrete's bulk temperature. Guessing from ambient temperature ignores the heat generated by hydration and the materials in the batch, and checking the truck’s gauge doesn’t provide a valid measure of the concrete’s actual temperature.