Compression Curves and Compression Indices of Compacted Montmorillonitic and Kaolinitic Soils

The engineering behaviour of fine-grained soils is a dominant function of their clay mineralogical composition. Based on their dominant clay mineralogical composition, the natural fine-grained soils may be grouped as montmorillonitic soils, kaolinitic soils and montmorillonitic-kaolinitic soils. This article presents the e-log σ' behaviour and compression indices of compacted montmorillonitic and kaolinitic soils at salient points along their compaction curves. It is shown that in spite of having almost the same liquid limit and or plastic limit, compacted montmorillonitic and kaolinitic soils exhibit vastly different e-log σ' behaviour and compression indices, irrespective of the placement conditions. It is illustrated that the compacted montmorillonitic soils exhibit higher compression indices than the compacted kaolinitic soils under any placement condition. The results from the present study are hoped to have practical values while selecting the type of soil and or placement conditions for better performance of geotechnical structures where compaction is preferred to be adopted.