Relationships of Atterberg Limits to Some Other Properties of Illinois Soils

Multiple correlations were determined between liquid limit, plastic limit, and plasticity index and various combinations of standard physical and chemical determinations (cation‐exchange capacity, percent of organic carbon, percent of <0.002‐mm. clay, percent of montmorillonite in the clay separate, percent of illite in the clay separate, and percent of 0.05‐ to 0.002‐mm. silt) on a wide range of Illinois soils. Multiple correlation coefficients of 0.959, 0.887, and 0.938 were obtained between liquid limit, plastic limit, and plasticity index, respectively, and three soil properties (percent of organic carbon, percent of clay, and percent of montmorillonite in the clay separaate), indicating that there is a very close relationship between Atterberg limits and these three soil properties. If additional soil properties, such as percent of silt and percent of illite in the clay separate, are included in the analysis the correlation coefficients are increased only slightly. Lower, but highly significant correlations were also obtained between each of the Atterberg limits and cation‐exchange capacity, and a combination of percent of organic carbon and percent of clay.