ACI Certification Practice Exam

What is the minimum concrete cover required around the temperature sensor when measuring the temperature of fresh mixed concrete?

1. 1 inch (25mm)

2. 2 inches (50mm)

3. 3 inches (75mm)

4. 4 inches (100mm)

The correct answer is: 3 inches (75mm)

The minimum concrete cover required around the temperature sensor when measuring the temperature of fresh mixed concrete is 3 inches (75mm). This specification is important to ensure accurate readings and to protect the sensor from the effects of environmental factors and thermal gradients that could influence the measurement of the concrete's temperature during the curing process. Having an adequate concrete cover helps in isolating the sensor from external influences, such as air temperature and wind, which can distort readings if the sensor is too close to the surface. A cover of 3 inches is generally considered sufficient to mitigate these effects, ensuring that the sensor provides a reliable representation of the concrete's internal temperature. Proper placement and coverage are crucial for achieving accurate monitoring, which is essential for evaluating the hydration process and strength development of the concrete. While the other options suggest varying covers, they either do not meet standard practice or are unnecessarily excessive for the purpose of temperature measurement.