Free swell ratio and clay mineralogy of fine-grained soils

The dominant clay minerals present in fine-grained soils control the physical and engineering behavior of the soils. Determination of the dominant clay minerals in the soils, at present, requires procedures involving sophisticated instrumentation and the knowledge to interpret the results from such tests. A user-friendly approach based on free swell ratio, defined as the ratio of the equilibrium sediment volume of 10-g oven dried soil in distilled water to that in carbon tetra chloride, has emerged as a simple methodology to predict the clay mineral(s) present in the soil as either montmorillonitic or kaolinitic type quite satisfactorily. The validation of the proposed free swell ratio method has been done with exhaustive experimental data.