## 4 Conclusions  
In this study, the effect of clay mineralogy on the interrelationships among Fall cone and Casagrande liquid limit, plasticity index, water content ratio, undrained shear strength, liquidity and flow indices were investigated. In this regard, three types of clay (_CaM_, \(K\) and _S_) were mixed with _NaM_ to obtain soils with different plasticity characteristics. _NaM_ clay was mixed with three types of clay at eleven different contents, ranging between 0% and 100% by an increment of 10% by weight.  
The relationship between cone penetration depth and water content was individually investigated for solid, semisolid, plastic and liquid states. The amount of cone penetration depth that separates the semisolid state from the plastic state and the plastic state from liquid state was found to be 2 and 20 mm, respectively. Meanwhile, the lowest water content for transition from plastic state to liquid state was measured at 45% and 200% for _NaM_-_S_ and _NaM_-_CaM_ mixtures, respectively. In the solid state, in all mixtures, generally with the initial water content, the amount of cone penetration depth with the increasing water content remained at a very limited level.  
The relationships among undrained shear strength (_S_\(u\)), water content (_w_) and cone penetration depth (_d_) were obtained for three types of mixtures. Due to the high plasticity of the mixtures ranging from 100% _NaM_ to 100% _CaM_, the above-mentioned relationship showed a similar behavior. With increasing water content, while the amount of cone penetration depth decreased, undrained shear strength values increased. Later on, the added water content led to an increase in the amount of cone penetration depth again and a decrease in undrained shear strength. In the _NaM_-_K_ and _NaM_-_S_ mixtures, the initial and final water content values showed a large scatter since the plasticity of mixtures ranged from very high to very low levels.  
Additionally, the relationships among _S_\(u\)-_w_-_L_I_ were obtained for three types of mixtures. Initially, low _S_\(u\) values and negative _L_I_ values were obtained at very low water contents. _S_\(u\) values and _L_I started to increase with increasing water contents. As the water contents continued to increase, the _L_I values increased while the _S_\(u\) values decreased. Since _NaM_ and _CaM_ clay mixtures have similar plasticity properties, the difference between the _S_\(u\)-_w_-_L_I_ behaviors was quite small, while the situation was the opposite for _NaM_-_K_ and _NaM_-_S_ mixtures. In _NaM_-_S_ mixtures, the water content at 100% _NaM_ was 460% with a corresponding _L_I of 2.05, while for 100% \(S\) the highest water content was 46% with an _L_I value of 3.60. For 100% _NaM_, the undrained shear strength value of 171.89 kPa was obtained at 64% water content and an _L_I value of \(-\)0.02, while the greatest undrained shear strength of 9.28 kPa for 100% \(S\) was obtained at 31.65% water content and an _L_I value of 0.37.  
Flow index-_L_ and flow index-_PI_ relationships were obtained for all mixtures by using both Casagrande and Fall cone test results. The flow index-_LL_ relationships were exponential with high coefficients of determination (\(R^{2}\) > 0.72 and \(R^{2}\) > 0.76) in both Casagrande and Fall cone test results, respectively. Flow index values obtained usingthe Fall cone test results were much higher than the values obtained by the Casagrande test results. According to experimental results, it was observed that the interdependence between undrained shear strength, liquidity index, log liquidity index and flow index is not unique due to the different physical and chemical properties of clays. Finally, this study will certainly be of interest to geotechnical researchers and engineers to understand the benefits of empirical equations proposed in the literature.  
This research received no external funding.