ACI Concrete Strength Testing Technician Practice Test

What is the compressive strength range for which unbonded caps may not be used for acceptance testing?

1. Above 500 psi and below 2000 psi

2. Below 1500 psi and above 12,000 psi

3. Below 1000 psi and above 10,000 psi

4. Below 800 psi and above 15,000 psi

The correct answer is: Below 1500 psi and above 12,000 psi

The compressive strength range for which unbonded caps may not be used for acceptance testing is identified as below 1500 psi and above 12,000 psi. Unbonded caps are designed for use in a general range of concrete strength, typically effective for compressive strengths that are lower and more moderate. When testing concrete with strengths below 1500 psi, the risks of not achieving proper bond between the cap and the sample increases, leading to inconsistent or inaccurate results. Similarly, for very high-strength concrete above 12,000 psi, the material properties and behavior can be significantly different, which also diminishes the effectiveness of unbonded caps in maintaining a reliable bond during the testing process. This information is crucial for ensuring that the testing methods align with the characteristics of the concrete being tested. It ensures that both lower and higher strength samples are tested using appropriate methods to provide the most accurate assessment of compressive strength.