Frequency-dependent electrical mixing law behavior in spherical particle composites

M. A. Campo, L. Y. Woo, T. O. Mason*, E. J. Garboczi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The electrical properties of cement-based composites with mono-size conductive (steel) or insulating (glass) spherical inclusions were investigated by combined 2-point impedance spectroscopy and 4-point dc resistance measurements. The matrix was ordinary Portland cement (w/c = 0.4; cured for 7 days). Particle loading was varied over an extended range to as high as 42% volume fraction. The steel particle composites behaved like the glass particle composites at dc and low ac frequencies; conductivity decreased with increasing particle loading. Under ac excitation, however, the steel particles were rendered conductive; conductivity increased dramatically with particle loading. The results were analyzed in terms of various mixing laws and effective media theories and the proposed "frequency-switchable coating model," which accounts for the unusual frequency-dependent behavior of the steel particle composites.

Original languageEnglish (US)
Pages (from-to)49-56
Number of pages8
JournalJournal of Electroceramics
Issue number1
StatePublished - Oct 2002


  • Cement
  • Composites
  • Electrical conductivity
  • Impedance
  • Mixing laws

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Mechanics of Materials
  • Electrical and Electronic Engineering
  • Materials Chemistry


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