A field density gauge that sends gamma radiation into the mat from a small cesium-137 source and counts what scatters back to its detectors; denser material returns fewer counts. On asphalt it is run in backscatter mode, with the source sitting just at the surface, and a reading takes about a minute. Readings must be correlated to cores for each mix, and the gauge requires a license, a trained operator, a dosimeter badge and locked storage.
Nuclear gauge correlation's off a point and a half from the cores, redo it before any of these numbers go toward pay.
Crews call it the nuke, and it never rides loose in a pickup bed: it is chained and locked in its case, or somebody loses a license.
Also heard as
- nuke gauge
- nuke
- Troxler
Related terms
Shoot
To take a reading with a nuclear gauge or infrared gun, as in shooting density or shooting a load's temperature.
Density
How tightly a compacted asphalt layer is packed, reported as a percentage of its maximum theoretical density.
Core
A cylinder of pavement drilled out of the finished mat and sent to the lab for density and thickness.
Control strip
A short test section paved at the start of a job to set the rolling pattern and density target.