ACI Certification Practice Exam

When inserting the sensor into the sample, what should be done to the concrete around it?

1. Gently press the concrete around the sensor

2. Dig a hole for the sensor

3. Leave the concrete undisturbed

4. Fill the area around the sensor with water

The correct answer is: Gently press the concrete around the sensor

Gently pressing the concrete around the sensor is important for ensuring accurate measurements from the sensor. When a sensor is inserted into concrete, it needs to be properly seated in its position to establish good contact with the surrounding material. This helps in obtaining reliable readings by minimizing air pockets or gaps that can lead to erroneous data. By pressing the concrete gently, the sensor becomes better integrated with the surrounding medium, allowing it to effectively interact with the concrete's properties, such as temperature or moisture, depending on what the sensor is designed to measure. Other methods, like digging a hole for the sensor, might disrupt the integrity of the sample and lead to inaccurate results. Leaving the concrete undisturbed could result in inadequate contact, while filling the area around the sensor with water is not typical practice, as it can introduce variables that may affect sensor performance.