Evaluation of the sand-cone method for determination of the in-situ density of soil

A sand-cone method is commonly used to determine the density of compacted soils. The density of the compacted soil calculated from the sand-cone method could be correct, provided the calibration container has approximately the same size or volume and allows the sand to fall to approximately the same height as a test hole in the field. However, in most cases, the size or shape of the test hole is not exactly the same as that of the calibration container. This can result in a difference in the settlement or deposition of sand particles between the laboratory calibration and the field testing, which may cause an erroneous determination of the in-situ density. The sand-filling process is simulated in the laboratory and its effect on the determination of density is investigated. Artificially made holes with different depths and bottom shapes are prepared to simulate various shapes of the test hole in the field. Sands with different particle size distributions are used in the testing to examine how sand grain size influences the determination of density in the field. The error between the assumed and calculated densities is highly dependent on the types of sand used in the sand-cone method. This paper presents some guidelines for obtaining correct in-situ densities through the sand-cone method.