Soil plasticity determination using manafi method and apparatus

Abstract

Determination of soil plasticity is of great importance in geotechnical engineering projects. Consistency of soil can be expressed in terms of Atterberg limits of soils. Liquid limit and plastic limit tests are among the two most regular tests for determination of index properties of fine grain soils. Soil classification of fine grain soils is based on results of Atterberg limit tests. In addition, many engineering properties of soils can be correlated to the results of soil plasticity determination tests. Current standard methods for determination of soil plasticity have several issues that make their results unreliable in many cases. In this research, it is tried to address problems of conventional methods regarding soil plasticity determination, design a new apparatus for determination of liquid limit and plastic limit of soils, and standardise a new test method for determination of soil plasticity with more accuracy and reliability in comparison to conventional methods. Soil consistency is a qualitative phenomenon. In this regard, author?s suggestion for solving the problems related to the determination of soil plasticity is utilisation of qualitative research approach. Accordingly, the author has proposed a new test method and designed a new apparatus (Manafi Apparatus) for determination of soil consistency based on the nature of soil deformation utilising qualitative research approach, referred to as Manafi Method. In this technique, it is possible to determine the workability of soil at Atterberg limits and specify the consistency state of the soil. Ten different soils were selected carefully to cover a wide range of soils plasticity with plastic limits range from 18.64% to 30.78%, and the liquid limits range from 30.25% to 61.77%. The most differences between the results obtained by proposed method and standard methods were 2.38% and 1.94% of water content for liquid and plastic limits correspondingly. The experimental results obtained by designed apparatus confirmed the proposed method and provided more consistent results in soil plasticity determination in comparison to current standard methods (fall cone and thread rolling methods).