Diatomaceous Soils and Advances in Geotechnical Engineering—Part I

Abstract

Diatoms are microscopic algae with a skeleton called a frustule, formed chiefly of silica, and are found in almost all aquatic environments and climatic conditions. Diatomaceous soils (DSs) originate from frustule sedimentation. In civil works (design and construction), the uncommon values obtained from DSs are not completely understood. There needs to be more knowledge about the strength and compressibility of DSs. The stability of these deposits is still being determined. Definitions of substances such as diatoms, diatomaceous soils, diatomaceous earth, diatomaceous oozes, frustules, and diatomite need to be clarified. This document references construction processes that face problems such as differential settlements, pile rebounds, and irregular pore pressures due to frustules. This review analyzes multiple sets of results regarding the grain size distribution, specific gravity, consistency, plasticity, compressibility, and shear strength of DSs. It is concluded that the particle size distribution of DSs generally classifies them as silts. Particles are modified by the imposition of stresses (frustule breakage), which impacts compressibility. Microfossils take up stresses, restrict strains, and cause sudden increases in compressibility when their yield stress is exceeded. Currently, their strain mechanisms need to be better understood. The Gs decreases with increasing frustule content, given the high porosity of the skeletons. The intraparticle pores of the frustules explain the high liquid limit (LL) of DSs. DSs can have high shear strengths and large yield surfaces due to the “interlocking” phenomenon and the interparticle contacts’ high frictional component caused by their rough surface and high silica content.