Relationship between measured plastic limit and plastic limit estimated from undrained shear strength, water content ratio and liquidity index

Abstract

The detection of the plastic limit of clays is subject to human error. Several attempts have been made to correlate across studies the geotechnical properties of fine-grained soils (water content, liquidity index, shear strength, etc.). Based on the premise that the liquidity index and water content ratio can be correlated directly, an alternative method to obtain indirectly the plastic limit is suggested here. The present study investigated 40 natural clayey samples of various mineralogies and origins and other publicly available data, where Atterberg limits and undrained shear strength values obtained with the vane shear tests were given. The liquidity index and water-content ratio correlate very well for defined undrained shear strength values of the clays. Solving the liquidity index equation for the plastic limit, estimated plastic limit values obtained by the liquidity index/water-content ratio relationship were compared with laboratory plastic-limit values. Preliminary results based on 62 values show an exponential trend with a multiple regression coefficient of 0.79. The data need to be confirmed on a larger database, however.

Estimation of consistency limits of fine-grained soils via regression analysis: A special case for high and very high plastic clayey soils in Istanbul

“…It is found that the change in plasticity index in terms of LL and h can be obtained by Equation (14) and shown by Figure 18. 0.9062 for common analysis.…”

“…Comparisons with actual experimental dataset forms the first way of the confirmation process. In addition, PI = −9.7 + 0.015h + 0.74LL ( 14) The R 2 value of the most fitting equation is obtained as the discussion with the literature sources creates the second way. The first step of the confirmation process has been studied and explained before, together with the studies of the acquirement of the equation.…”

“…Cantillo and Pajaro [13] have presented a technical note including some correlation equations that are suggested to predict the swelling pressure based on the consistency limits with statistical methods. Spagnoli and Feinendegen [14] have used 40 different clay samples with different mineralogies and have performed some laboratory tests to evaluate the strength and consistency characteristics. Some solutions are conducted with the use of liquidity index depending on the estimated plastic limit values to verify the suggested relationships.…”

Surface chemistry, rheology and microstructure of as-received SHCa-1 hectorite gels

“…The yield stress is a measure of the gel strength or the strength of the microstructure forming the gel. This should be related to the plastic limit used to characterize the rheological properties of clay suspensions (Spagnoli & Feinendegen, 2017). The ageing behaviour characterizing the structural recovery behaviour in terms of yield stress vs. ageing time was also characterized.…”

Behavior of strip footing rested on undrained clay using consistency limits-based constitutive law

“…While Casagrande suggested an average (Cu) of 2.65 kN/m 2 considering the spread of the values depending of the apparatus of determination of LL, other authorities on the subject had proposed a range between 0.7 kN/m 2 and 2.8 kN/m 2 and suggested the use of the Casagrande apparatus for determining LL ( Sharma and Bora, 2003 ). It was remarked that the failure of undrained clay is self-weight-induced and the use of in-situ experimental setups to validate constitutive relations becomes difficult due to the impact of the weight of cone on the failure of clay ( Spagnoli and Feinendegen, 2017 ). Note, mechanical properties (Es, υ) of clay have been used in the previous studies as well as hydro-mechanical properties (LL, PL, and WC).…”