ACI Concrete Field Testing Technician - Grade I Practice Exam

What is the minimum and maximum time that the temperature measuring device should be in fresh concrete?

1. 1 to 3 minutes

2. 2 to 5 minutes

3. 3 to 8 minutes

4. 4 to 10 minutes

The correct answer is: 2 to 5 minutes

The correct range of time for the temperature measuring device to be in fresh concrete is 2 to 5 minutes. This duration is crucial to obtain an accurate representation of the concrete's temperature. Having the device in place for at least 2 minutes ensures that the sensor adjusts and stabilizes in the fresh concrete, allowing it to accurately reflect the temperature of the concrete mass. If the device is removed too quickly, it may not register the true temperature due to insufficient time for thermal equilibrium. Conversely, leaving the device for too long may cause heat discrepancies due to factors like groundwater movement, evaporation, or temperature changes in the surrounding environment. Thus, the 2 to 5-minute range balances the need for accurate measurements while minimizing disturbances that could skew results. This careful timing is part of standard testing protocols to ensure consistency and reliability in the results obtained from temperature measurements in concrete testing.