ACI Concrete Strength Testing Technician Practice Test

If suitable contact is not made between the specimen and bearing block surfaces, which of the following may be required?

1. Adjustment of specimen weight, use of water, changing apparatus, or recalibration

2. Use of shims, grinding, or capping

3. Application of adhesives, additional testing, or heating

4. Positioning of clamps, removal of dust, or repplacing components

The correct answer is: Use of shims, grinding, or capping

In the context of concrete strength testing, achieving suitable contact between the specimen and bearing block surfaces is essential for accurate results. When this contact is inadequate, various methods are employed to improve the surface interaction. Using shims, grinding, or capping serves to create a better fit between the specimen and the testing equipment. Shims can help adjust the height or alignment of the specimen, thus ensuring proper contact with the bearing surfaces. Grinding might be necessary to smooth out irregularities on either the bearing block or the specimen, facilitating a more uniform surface interaction. Capping involves placing a material such as a plaster or resin on the ends of the concrete specimen to provide a flat, even surface that guarantees effective contact with the testing apparatus. This approach is critical because uneven or improper contact can lead to incorrect load distribution during the test, resulting in inaccurate strength measurements. Properly preparing the surfaces helps to maintain the integrity of the testing process and ensures reliable quantification of the concrete’s compressive strength.