On swelling behaviours of a bentonite under different water contents

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7 Citations (Scopus)

Abstract

This study starts from a question: how would initial water content (wi) affect equilibrium swelling pressure (peq) of compacted bentonites in swelling pressure tests (ps tests)? However, discussions based on experiments involving a bentonite, Kunigel V1 (K_V1), are extended to the following issues: (a) the effect of wi on peq; (b) pore water density (ρpw); (c) the co-existence of crystalline and osmotic swelling; and (d) relation between peq and compaction tests (pc tests). It is revealed that wi has an insignificant effect on peq in general, although a significant effect may appear for relatively high wi and dry density (ρd) conditions. Two swelling types, crystalline swelling with basal spacing of montmorillonite (d001=1·0-1·9 nm) and osmotic swelling (d0011/44·0 nm), co-exist in a w range from 36 to 65%. With the fact that ρpw of K_V1 may range from 1·1 to 1·2 Mg/m3, it is expected that crystalline swelling may mainly govern peq in ps tests if the final dry density of a specimen (ρdf) is larger than 1·46 Mg/m3, while osmotic swelling may mainly govern if ρdf-1·05 Mg/m3. Together with the results of pc tests, the effects of wi on peq are explained by the proposed conceptual model.

Original languageEnglish
Pages (from-to)64-80
Number of pages17
JournalGeotechnique
Volume74
Issue number1
DOIs
Publication statusPublished - 2022 Apr 5

Keywords

  • apparent swelling pressure
  • basal spacing of montmorillonite
  • bentonite
  • clays
  • water content effect

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Earth and Planetary Sciences (miscellaneous)

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