Determination of Plastic Limit by Fall Cone Test for Soils with Different Grain Size Distribution

Compaction parameters and consistency limits are fundamental engineering properties considered in the design of geotechnical applications. It is important to compare these parameters derived from experimental studies with the equations proposed in the literature or alternative methods. This study determined the plastic limit values of soils with different grain size distributions and different consistency limits using the relationship between penetration depth and water content from the fall cone test, employing a cone with 30° and 80 g characteristics. The method for determining the plastic limits has been developed based on a wide range of data. It defines the water content corresponding to a 3 mm penetration of the cone into the soil as the plastic limit. The plastic limit values determined by the proposed method were tested with a comprehensive dataset compiled from literature studies. The results indicated a satisfactory correlation between the plastic limits determined by the tread rolling method and those determined by the proposed method (R2 = 0.76). Furthermore, the compaction parameters obtained from the standard compaction tests were investigated using univariate and multivariate regression analyses, with consideration given to the liquid and plastic limits determined from the fall cone tests. The findings indicate that the compaction parameters can be predicted with high coefficients of determination (R2 = 0.89) using the plastic and liquid limits determined from the relationship between water content and penetration depth in the fall cone tests.