Lesson 4/Learning Event 4
Learning Event 4
DESCRIBE USES OF THE NUCLEAR MOISTURE AND DENSITY GAGE
The nuclear moisture and density gage is a device that measures density and moisture contents of soil,
asphalt, and other materials. It is used extensively by engineers because of its labor saving advantage.
It is quick and provides accurate values, equal to present standard methods.
The nuclear device has gamma and neutron radiation sources. The gamma source measures density.
The less dense a soil, the less gamma radiation feedback occurs. The neutron radiation measures
hydrogen content. The neutron source will detect hydrogen elements within an object. (An example is
water (H2O) within a soil mass.) The more hydrogen detected, the higher the neutron reading.
However, organics can cause neutron readings to be inaccurate. Organics like decomposed trash, rotting
trees, topsoil, leaves, and algae can cause inaccuracies to the nuclear device readings.
Thus, to be used properly, the nuclear device must be handled by experienced, qualified personnel.
Handled properly, it is a safe and time efficient device that allows engineers to get adequate and
immediate density and moisture content readings on the project site.
See Figure 32 following.