Activation energy of conduction for use in temperature corrections on electrical measurements of concrete

Alex T. Coyle, Robert P. Spragg, Prannoy Suraneni, Armen N. Amirkhanian, Marisol Tsui-Chang, William Jason Weiss

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

The formation factor obtained through electrical resistivity measurements is becoming a popular method to determine transport properties of concrete. Resistivity measurements are dependent on multiple factors, including degree of saturation, pore solution conductivity, and temperature. The Arrhenius equation is used to correct electrical resistivity for temperature effects using an activation energy of conduction (E a-cond ). This parameter has been measured on a wide variety of materials, including pore solutions, pastes, mortars, and concretes (with a variety of saturation states). The reported values of E a-cond typically range from 9 to 39 kJ/mol. This article examines the factors affecting E a-cond in order to select an appropriate temperature correction. In this study, E a-cond was determined from data measured on various concrete mixtures used in transportation infrastructure applications as well as extracted and simulated pore solutions. The E a-cond of pore solutions remains relatively constant (an average value of 13.9 ± 1.5 kJ/mol) for typical pore solutions and was slightly lower than the E a-cond of saturated specimens (an average value of 15.8 kJ/mol). It was found that E a-cond increases as the degree of saturation of the specimen is reduced. Drying increases the ionic concentration of the fluid in the pores; however, this does not explain the changes in E a-cond . The effects of drying were determined to be primarily due to a change in the volume of the conductive fluid film in the concrete and in the connectivity of the fluid-filled pores. While it is better to directly measure the E a-cond of a concrete mixture, this is not always feasible or practical. In such cases, for pore solutions, a value of 13.9 kJ/mol can be used, and for saturated concretes, a value of 15.8 kJ/mol can be used. For concretes with a varying degree of saturation, the E a-cond can be estimated using the developed equation.

Original languageEnglish (US)
Pages (from-to)158-170
Number of pages13
JournalAdvances in Civil Engineering Materials
Volume8
Issue number1
DOIs
StatePublished - Feb 25 2019

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Keywords

  • Activation energy
  • Formation factor
  • Pore connectivity
  • Resistivity
  • Temperature correction

ASJC Scopus subject areas

  • Ceramics and Composites
  • Civil and Structural Engineering
  • Mechanics of Materials
  • Polymers and Plastics
  • Metals and Alloys
  • Materials Chemistry

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