Alterations of physical properties and microstructure of marine diatomite owing to variation of diatom content

Diatomite is a natural soil and comprises mainly clays and diatom frustules and is distributed generally in the marine environment. The presence of the diatom frustules imparts the diatomite physical properties different from those of common clays and sands, such as high Atterberg limits, low density, and high specific surface area. However, how the diatom frustules affect the physical properties of diatomite has yet to be established, especially from a microscopic perspective. This study linked the physical characteristics and microstructure of diatom frustules by performing laboratory tests on diatom-kaolin mixtures with different diatom contents. The results reveal the considerable influence of the diatom content on the physical characteristics of diatomite, with the feature alterations explained by microstructural investigation. The current understanding of diatomite in soil classification is also discussed based on the special physical behaviours and microstructure caused by the diatom frustules. This study provides a comprehensive description of the physical characteristics influenced by different diatom content associated with the microstructure, which reveals the essence of the physical behaviors of diatomite.