Determining Soil Plasticity Utilizing Manafi Method and Apparatus

• Published in: Geotechnical testing journal 2022-07, Vol.45 (4), p.797-818
• Main Authors: Manafi, Masoud S. G., Deng, An, Taheri, Abbas, Jaksa, Mark B., HB, Nagaraj
• Format: Article
• Language: English
• ISSN: 0149-6115; 1945-7545
• DOI: 10.1520/GTJ20210235

Soil plasticity is one of the essential index properties required for classifying soils in geotechnical engineering practice. Determination of plasticity properties of soils is also critical for correlation with their engineering properties such as shear strength, permeability, and compressibility. However, present standard test methods for soil plasticity suffer, to different extents, from operator-dependency and inconsistency. This study introduces a new technique utilizing a combined qualitative and quantitative approach for soil property determinations, namely the Manafi Method and Apparatus. The method is proposed as an alternative technique to determine the liquid and plastic limits of soils. The proposed technique is instrumented with a new soil extrusion device to quantify the workability of soils and is calibrated to translate the workability to their liquid and plastic limits. The method is applied to seven soils of varying particle sizes and plasticity to determine the liquid and plastic limits, and the results are compared with those obtained by the conventional methods. The outcomes suggest that the new technique provides a more precise and reliable means of soil plasticity determination in the studied samples.