ACI Concrete Strength Testing Technician Practice Test

What is a requirement for bearing blocks used in the third-point loading method?

1. Forces must be applied eccentrically

2. Forces must be applied parallel to the face

3. Forces must be applied perpendicularly without eccentricity

4. Forces can be applied at any angle

The correct answer is: Forces must be applied perpendicularly without eccentricity

In the third-point loading method, the requirement for bearing blocks is that forces must be applied perpendicularly without eccentricity. This is essential because applying the load perpendicularly ensures that the stress distribution under the load is uniform and does not introduce additional bending moments or shear forces that could affect the results of the test. When forces are applied perpendicularly, it allows for a straightforward evaluation of the compressive strength of the concrete sample being tested. If eccentric forces were to be applied, it could lead to inaccurate representations of the material's strength characteristics, as the load would not be uniformly distributed, potentially skewing the data. This clarity in loading conditions is critical for achieving reliable test results and maintaining compliance with standard testing protocols.