How long should the thermometer be submerged in concrete?

When measuring the temperature of freshly mixed concrete, it is important to ensure that the thermometer is submerged long enough to obtain an accurate reading of the concrete's temperature. Submerging the thermometer for at least 2 minutes allows the device to equilibrate with the concrete mix, thus providing a reliable measurement.

This timeframe is sufficient for the heat transfer to occur, leading to a stable reading. If the thermometer is not submerged adequately, it may result in an inaccurate temperature measurement, which is critical for assessing the concrete's properties, as temperature can affect the hydration process and the overall quality of the concrete.

The range of 2 to 5 minutes specified in the correct answer helps balance efficiency with the need for accuracy in temperature measurements, ensuring that concrete testing protocols align with established standards.