ACI Concrete Strength Testing Technician Practice Test

Depressions in the ends of the cylinders exceeding what depth must be corrected prior to testing?

1. 0.10 in.

2. 0.15 in.

3. 0.20 in.

4. 0.25 in.

The correct answer is: 0.20 in.

In the context of concrete strength testing, it is essential to ensure that the ends of the test cylinders are flat and smooth to obtain accurate compressive strength measurements. When depressions are present at the ends of the cylinders, they can significantly affect the area of contact between the cylinder and the testing machine. This misalignment can lead to a non-uniform load distribution during the testing process, which may result in inaccurate strength readings. The industry standard stipulates that any depressions exceeding a specific depth must be corrected to ensure the integrity of the test results. For this scenario, a correction depth of 0.20 inches has been established. If the depressions exceed this depth, corrective measures such as machining or filling with a non-shrink material must be undertaken to achieve a suitable end condition on the cylinder. By adhering to this criterion of 0.20 inches, technicians can minimize the risk of erroneous results and maintain the reliability of compressive strength testing, which is crucial for evaluating the performance of concrete in construction applications.