North Carolina General Contractors Practice Exam

Which soil testing method is considered the most advantageous?

1. Proctor test

2. Sand cone test

3. Nuclear density test

4. Gravel density test

The correct answer is: Nuclear density test

The nuclear density test is recognized as the most advantageous soil testing method for several reasons. This technique provides a quick and accurate measure of the moisture content and density of soil in situ, meaning it can be performed on-site without the need for excavation or sample transportation. This method utilizes the principles of nuclear radiation, where a radioactive source emits gamma rays that penetrate the soil. The intensity of the radiation that returns to the detector is proportional to the density of the material, allowing for immediate determination of soil properties. This immediate feedback is crucial in construction and engineering projects where timely decisions must be made about the soil's suitability for foundations or other structures. Additionally, the nuclear density test can be used for various types of soils and is less susceptible to errors caused by soil layering or changing moisture conditions since the measurement occurs in place. The efficiency gained through fewer field tests and shorter project timelines adds to its advantage as well. In contrast, other testing methods like the Proctor test, sand cone test, and gravel density test often involve more labor-intensive processes, require more time to deliver results, or are limited to specific soil types or conditions. This makes the nuclear density test a preferred choice in many scenarios.