Which of the following best characterizes the function of a Nuclear Gauge?

A Nuclear Gauge is primarily used to assess the density of materials, including asphalt layers, by utilizing the principles of nuclear radiation. The gauge emits radiation that penetrates the material being tested. By measuring the amount of radiation that is returned after passing through the material, the gauge can determine the density of the asphalt layer. This is crucial for ensuring the proper compaction of asphalt, which affects the durability and longevity of the pavement.

Measuring moisture content in aggregates is an important aspect of asphalt paving; however, it is not the primary function of a Nuclear Gauge. The device can provide indirect information about moisture but is not designed to measure it specifically. Testing dynamic shear rheology relates to the flow properties of asphalt mixtures under load and is typically done using different equipment designed for rheological testing, rather than a Nuclear Gauge. Providing radiation measurement for soil addresses another domain of geotechnical studies, which doesn't align with the primary use of the gauge in asphalt applications. Therefore, the characterization of a Nuclear Gauge as a tool for assessing density in asphalt layers is accurate and reflects its most significant role in paving operations.