Indirect measurement of relative density by cone penetration testing

3 Indirect measurement of relative density by cone penetration testing 

The relative density of the hydraulic fill can also be determined by indirect testing. Especially for sand layers deeper than 2 m below the surface or below the phreatic surface, it may be virtually impossible to determine the in situ density using the direct measurement methods. In granular material, the only option for taking undisturbed samples is by freezing the soil prior to the sampling. Often the Cone Penetration Test (CPT) is used to determine the relative density of those submerged or deep sand layers. Over the years several correlations have been established between cone resistance and relative density. 

Those eorrelations were based on calibration chamber tests on sands. Some commonly used reference research sands along with their main properties are listed in Table 8.3. 

It is noted that parameters can differ considerably depending on the type and mineralogy of the subject sand. 

The resulting correlations are only valid for the type of sand that has been tested in the calibration chamber. Additionally, special attention should be paid to  

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