The classification of microstructures of clay soils

SUMMARY This paper presents the results of experimental studies on the microstructure of clay soils, using scanning electron microscopy. Approximately 300 samples of clay soils of various ages, origin and degree of lithification have been analysed. Five main types of microstructure have been identified in clay soils of sedimentary origin, i.e. honeycomb, skeletal, matrix, turbulent and laminar. Among clay soils of sedimentary origin and hydrothermal origin three types of microstructure were distinguished; domain, pseudoglobular and globular. In natural environments, microstructures of mixed features have been found, i.e. honeycomb‐matrix, honeycomb‐skeletal, turbulent‐matrix, etc. The detailed description presented of the different microstructural types comprising morphology and quantitative calculations, shows a close relationship with mineral composition, origin and degree of lithification. In addition physical and mechanical properties as well as the resistance and deformation indices of clay soils have been found to be related to microstructural features.