Oedometric Behavior of Diatomite–Kaolin Mixtures

Abstract

This paper discusses the results of an experimental program to study the compressibility of mixtures of kaolin and diatom microfossils, particularly the effects of diatomite content (DC) on consolidation, swelling, and long-term compression. Thirty long- and short-term oedometer tests were performed on laboratory-sedimented, preconsolidated specimens of diatomite–kaolin (D-K) mixtures. The compression and swelling of the mixtures were affected by the DC, especially when the DC was 60% (by dry mass) or greater. The effect of preconsolidation on the compression curve was much less evident as DC increased. For soils with diatoms, Cα does not have the same meaning of secondary compression or creep as for fine-grained soils. Greater Cc and Cα values with increasing DC were explained by contributions from three mechanisms that may overlap during loading: faster pore pressure dissipation due to larger interparticle and intraparticle porosities, rearrangement and bending of kaolin particles around frustules, and elastic compression and eventually breakage of frustule particles.