Digital Penetrometer method has several advantages over the Casagrande method. It is easier to perform this test and the results are not so dependent on the design of the apparatus or the judgement of the operator. It is applicable to a wider range of soils. The test is based on the relationship between moisture content and the penetration of the cone into the soil sample. The moisture content at a given depth of penetration of the cone is taken as the liquid limit. As an inferential test, empirical correlations have been developed to assess the shear strength of soils at liquid limit. Reduces operator error • Applicable to a wide range of soils • Gives reproducible test results • Provides direct measurement of penetration.
Ref. Standards IS:2720 (Part 5) BS 1377