North Carolina Building Contractor License Practice Exam

For compacted fill, what is the requirement in terms of density?

1. At least 70% of proctor density

2. At least 85% of proctor density

3. At least 90% of proctor density

4. At least 95% of proctor density

The correct answer is: At least 90% of proctor density

Compacted fill is critical in construction because it ensures stability and load-bearing capacity for structures. The requirement that compacted fill reaches at least 90% of proctor density is significant, as this figure indicates a high level of compaction that reduces voids and enhances soil strength. Proctor density, established through an effort to determine the maximum density of soil for a given moisture content, serves as a benchmark for assessing the effectiveness of the compaction process. Achieving 90% or more of this density means that the soil has been compacted sufficiently to support structural loads, minimizing the risk of settling or shifting during and after construction. Properties like drainage, shear strength, and compressibility improve with higher density, which is crucial for preventing future structural issues. Therefore, requiring at least 90% of the proctor density ensures that the foundation and subgrade are adequately prepared for the intended construction while adhering to best practices in soil engineering. This standard is aligned with engineering and construction industry norms and codes, making it a necessary criterion for compacted fill in North Carolina and many other states.