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This test method determines the liquid limit, plastic limit, and the plasticity index of soils. These test results can be used to classify fine-grained soils and the fine-grained fraction of coarse-grained soils according to the Unified Soil Classification System (USCS). The liquid limit, plastic limit, and plasticity index can be used to correlate compressibility, hydraulic conductivity, compactibility, shrink-swell and shear strength of soils.

 

The test for plastic limit uses the multi-point method (Method A) if more than one measurement is specified and the one-point method (Method B) if only one measurement is specified.

 

Data entry and calculations for this test are performed on the Classification form described in the next section. After the data and calculations have been performed the results are displayed in a test report as described in the reporting section below. The format of this report is controlled by the geotechnical template used for the test.

 

The methodology and calculations for this test adhere to "ASTM D2487-06 Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)" and "ASTM D4318-10 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils". For more detailed information on the methodology and calculations please review these standards.