Volume 4, Issue 4 (December 1981)
Nondestructive Soil Bulk Density Measurements by X-ray Attenuation
Nondestructive density measurement of soil samples in the laboratory has a number of important applications. It can be used to monitor the progress of soil settlement through water and subsequent consolidation to a final equilibrium state, with or without an additional applied load. It can provide information on moisture content distribution in laboratory samples, in both static and changing conditions, and on soil structure in undisturbed cores. This paper describes a nondestructive technique for density measurement that can achieve accuracies in measured soil density of the order of ± 0.005 g/cm3 and a spatial resolution of ± 1 mm. The technique uses an X-ray system with a scintillation detector and counter assembly to record the radiation transmitted through the soil sample. This is converted to a density value by empirical calibration. The principles of the method are described with consideration given to the variables of the measuring system, the beam collimation, and the sample geometry. The method is shown to be reliable and versatile.