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Modelling the influence of the interfacial zone on the D.C. electrical conductivity of mortar

E.J. Garboczi and D.P. Bentz
National Institute of Standards and Technology
Building Materials Division, 226/B350, Gaithersburg, MD 20899

L.M. Schwartz
Schlumberger-Doll Research, Old Quarry Road
Ridgefield CT 06877-4108

Abstract

The interfacial zone separating cement paste and aggregate in mortar and concrete is believed to influence many of the properties of these composites. The available experimental evidence, obtained on artificial geometries, indicates that the D.C. electrical conductivity of the interfacial zone, because of its higher porosity, may be considerably larger than that of the bulk cement paste matrix. This paper presents the theoretical framework for quantitatively understanding the influence of the interfacial zone on the overall electrical conductivity of mortar, based on realistic random aggregate geometries. This understanding is also used, via an electrical analogy with Darcy's law, to make predictions about the effect of the interfacial zone on fluid permeability as well. The results obtained for mortar should also pertain to concrete.

• Introduction
• Constituent properties in the three phase model
• Periodic and random models for mortar
• Electrical Conductivity Results
• Comparison with experimental evidence
  • Electrical conductivity
  • Fluid permeability
• Discussion of Future Work
• Summary
• References