ACI Concrete Strength Testing Technician Practice Test

What is the minimum thickness a pad must have in relation to the cylinder diameter in ASTM C1231?

1. 1/16 in.

2. 1/8 in.

3. 1/4 in.

4. 1/2 in.

The correct answer is: 1/16 in.

The minimum thickness of a pad in relation to the diameter of the cylinder as specified by ASTM C1231 serves a critical purpose in ensuring accurate strength testing of concrete. It establishes guidelines to promote uniform distribution of load during testing, thereby preventing any localized failure that could affect the integrity of the test results. In this context, the standard specifies that the pad must have a minimum thickness of 1/16 inch. This thickness is sufficient to provide adequate support while ensuring that the pad does not excessively compress under load, which could lead to misleading results. The thinness of the pad allows for better alignment and transfer of stress from the cylinder to the testing apparatus. The other choices provided represent greater thicknesses that exceed the specified minimum, which may not be necessary and could lead to complications in the testing process. A pad that is too thick could create its own issues, such as differential compression and potential adherence to the test cylinder, which would compromise the reliability of the obtained strength measurements. Thus, the specification of 1/16 inch is carefully considered to strike a balance between providing necessary support and ensuring that the pad itself does not interfere with the accuracy of the testing procedure.