North Carolina Building Contractor License Practice Exam

What is the requirement for strength tests in terms of the number of cylinders tested?

1. Average of three cylinders

2. Average of two cylinders

3. Single cylinder test

4. Average of four cylinders

The correct answer is: Average of two cylinders

The requirement for strength tests for concrete involves the averaging of the strength of two cylinders. This practice is based on industry standards that specify testing compressive strength using multiple samples to ensure the reliability and accuracy of the results. Testing two cylinders provides a method to assess variability within a single batch of concrete, allowing for a more reliable representation of the material’s strength characteristics. Averaging the strengths from two cylinders also helps account for any potential anomalies or inconsistencies that might occur in individual samples, promoting a more standardized and dependable assessment. In addition, industry codes and testing protocols often align with this approach to ensure that construction practices meet safety and performance criteria. This kind of averaging is essential in quality control processes where slight differences in cylinder strength can effectively influence decisions on whether the concrete meets specified construction standards. Thus, averaging the strength of two cylinders provides a balanced and representative measure of the material’s performance, which is crucial in the context of construction projects in North Carolina and beyond.