An interesting and useful equipment to determine compation acceptation of earthworks are gauges such as Troxler and Humboldt. They using the physical basis of ionizing radiation interaction with matter, which allows to measure soil density very quickly and very accurately.
Employees performing the test are obliged to have dosimeters and they must have appropriate qualifications and the company must be authorized by the National Atomic Agency.
Performing additional measurements with nuclear gauge (in the US specifications are the main tests) is important in urgent cases, when an immediate result is needed, e.g.
- the test result drive cylinder is after 1 working day, when the sample will be delivered to the laboratory, dried, weighed and the value will be compared with the Proctor's test
- VSS static plate testing lasts approx. 40 min - 1h and requires later analyzing of the results in the laboratory, which results also after 1 working day, because the emplpyee has to return back to the laboratory. In addition, construction equipment (eg. a truck) is required for the VSS test, which is blocked for the duration of the measurement.
- examination with the nuclear gauge enables delivery of the Is result in a few minutes (measurement time - 1 min, time of the zone supervised around the meter - 4 min) - the screen displays immediately the absolute value of moisture and density and % of maximum volumetric density comparing with the Proctor test
Nuclear gauge can be used wherever there is any doubt about the compaction of the soil, because the measurement error of the device is very small, especially since it is calibrated daily on a standard block.