Which method is commonly used to measure the density of asphalt during construction?

Answer: C — Nuclear density gauge

The nuclear density gauge is widely recognized as a common method for measuring the density of asphalt during construction. This equipment works by emitting radioactive isotopes that interact with the asphalt material, enabling the gauge to assess both the moisture and density of the asphalt layer being laid down. The advantage of using a nuclear density gauge lies in its ability to provide immediate, accurate measurements on-site, which is crucial for ensuring that the asphalt is compacted correctly and meets the requisite density specifications for durability and performance. Other methods, although useful, do not compare in terms of efficiency and accuracy for this specific application. Digital scales and manual gauges do not provide the level of insight required for asphalt density, as they may not be specifically designed for this purpose. A vibrating compactor is primarily a tool for the compaction process rather than a measurement device, thus it does not measure density directly. This makes the nuclear density gauge the preferred choice for asphalt density measurement during construction.