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Frequency-Dependent Electrical Mixing Law Behavior in Spherical Particle Composites



M A. Campo, L Y. Woo, T Mason, Edward Garboczi


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 vol%. 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-switching coating model, which accounts for the unusual frequency-dependent behavior of the steel particle composites.
Journal of Electroceramics
No. 1


cement, composites, electrical conductivity, impedance, mixing laws


Campo, M. , Woo, L. , Mason, T. and Garboczi, E. (2002), Frequency-Dependent Electrical Mixing Law Behavior in Spherical Particle Composites, Journal of Electroceramics, [online], (Accessed June 16, 2024)


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Created September 30, 2002, Updated October 12, 2021