North Carolina Building Contractor License Practice Exam

How often should strength test samples for concrete be taken?

1. Every 10 yards

2. Once for each 100 yards

3. Once for each 150 yards or daily

4. Every 20 yards

The correct answer is: Once for each 150 yards or daily

The proper frequency for taking strength test samples for concrete is determined to ensure that the material meets the required performance standards for the construction project. Taking samples once for each 150 yards or daily is a commonly accepted practice, as this allows for consistent monitoring of concrete quality throughout the pouring process. Concrete can vary due to factors such as the mix design, moisture content, and batching variations. By sampling this frequently, contractors can ensure that any issues with the concrete's strength can be identified and addressed promptly before it impacts the structural integrity of the project. Additionally, this sampling approach aligns with national standards, such as those from the American Concrete Institute (ACI) and ASTM International, which advocate for systematic testing throughout the construction process. Sampling every 10 yards, every 20 yards, or once for 100 yards would not offer the same level of oversight and could potentially lead to inadequate monitoring of concrete quality, increasing the risk of structural failures. The 150 yards or daily sampling strategy strikes a balance between thoroughness and practicality, making it the most effective option outlined.