The use of nuclear moisture/density meters on materials with well-defined density gradients
G. Hamory, P. R. Duncan
Dec 1, 1992
Citations
0
Citations
Journal
Road & Transport Research
Semantic Scholar
Key Takeaway Key Takeaway: Nuclear moisture/density meters can accurately measure soil density in road construction, but their backscatter mode may bias results towards the upper horizon.
Abstract
Nuclear moisture/density meters are used extensively in road construction to measure the in situ density of soils. With most of the current models, tests may be carried out in either the backscatter or direct transmission modes. The User's Manual of some manufacturers suggests that in the backscatter mode the densities obtained by the nuclear meters are biased towards the density of the upper horizon. This was also the opinion of experienced laboratory personnel operating the devices. This investigation confirmed the bias associated with the backscatter mode. The ability of the nuclear meters to measure in the direct transmission modes the average density of the soil over the selected depth was also demonstrated. Upper surface bias was not apparent in the direct transmission modes. The investigation also supported the validity of the method of calibrating nuclear meters on the standard density blocks as employed by Main Roads Western Australia (MRWA). The manufacture of calibration blocks of slabs of natural stone offers advantages and should be considered.