Use of fall-cone flow index for soil classification: a new plasticity chart

Paul J Vardanega, Stuart K Haigh, Brendan O'Kelly

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Use of the Casagrande-style plasticity chart to classify fine-grained soils using Atterberg’s liquid and plastic limits is ubiquitous in geotechnical engineering. This classification is dependent on the thread-rolling and Casagrande-cup tests, which are both more operator dependent than the fall-cone liquid limit test. This paper shows that the slope of the data acquired during the fall-cone liquid limit test (the fall-cone flow index) can be used to redraw the plasticity chart, thus allowing classification of fine-grained soils to be achieved solely from fall-cone liquid limit data.
Original languageEnglish
Number of pages8
Early online date8 Mar 2021
Publication statusE-pub ahead of print - 8 Mar 2021


  • laboratory tests
  • soil classification
  • standards & codes of practice
  • statistical analysis

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