Behavior of rigid-soft particle mixtures

Jong Sub Lee*, Jake Dodds, J. Carlos Santamarina

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

139 Scopus citations


Mixtures of rigid sand particles and soft fine-grained rubber particles are tested to investigate their small and large-strain responses. Mixtures are prepared with different volumetric sand fraction sf to identify the transition from a rigid to a soft granular skeleton using wave propagation, k0 loading, and triaxial testing. Deformation moduli at small, middle, and large strains do not change linearly with the volume fraction of rigid particles; instead, deformation moduli increase dramatically when the sand fraction exceeds a threshold value between sf=0.6-0.8 that marks the formation of a percolating network of stiff particles. The friction angle increases with the volume fraction of rigid particles. Conversely, the axial strain at peak strength increases with the content of soft particles, and no apparent peak strength is observed in specimens with low sand fraction (sf≤0.6). The presence of soft particles alters the formation of force chains. Although soft particles are not part of high-load carrying chains, they play the important role of preventing the buckling of stiff particle chains.

Original languageEnglish (US)
Pages (from-to)179-184
Number of pages6
JournalJournal of Materials in Civil Engineering
Issue number2
StatePublished - Feb 2007
Externally publishedYes


  • Elasticity
  • Mixtures
  • Porosity
  • Shear waves
  • Velocity

ASJC Scopus subject areas

  • Mechanics of Materials
  • Building and Construction
  • General Materials Science
  • Civil and Structural Engineering


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