North Carolina Building Contractor License Practice Exam

Samples for strength tests of each class of concrete placed each day shall be taken no less than once a day, nor less than once for each what percentage of concrete?

1. 5%

2. 10%

3. 15%

4. 20%

The correct answer is: 10%

The requirement for taking samples for strength tests of concrete is based on industry standards and practices outlined in the specifications for concrete work. In North Carolina, and generally within the construction industry, the guideline is that samples should be taken daily and also based on a percentage of the concrete placed. Taking samples for strength tests helps ensure the quality and performance of the concrete. The correct guideline specifies that samples must be taken at least once for each 10% of the total quantity of concrete being placed. This means that if a contractor is pouring a large volume of concrete, they should take samples at intervals that ensure adequate testing and monitoring of the concrete’s strength. Sampling at this percentage helps ensure that variations in the mix or potential problems can be detected and addressed promptly, maintaining the structural integrity of the project. Other percentages are either excessive or insufficient, failing to balance quality assurance with practical sampling frequency, which is why the correct answer reflects the standard practice of sampling at 10%.