Impedance spectroscopy as a tool for moisture uptake monitoring in construction composites during service

Sotirios Grammatikos, Richard J. Ball, Mark Evernden, Ryan Jones

Research output: Contribution to journalArticlepeer-review

28 Citations (SciVal)


This is a first study comparing dielectric spectroscopy and gravimetric measurements of moisture uptake in pultruded glass fibre reinforced polymers (FRPs). Specimens were subjected to sub-Tg hygrothermal aging for 224 days. Impedance spectra in the frequency range 0.1 Hz to 10 MHz were captured during exposure and compared with gravimetric measurements. Moisture concentration was found to increase the FRP’s dielectric permittivity monotonically and decrease bulk resistance. High quality dielectric data was obtained as moisture uptake is independent of inherent changes suggested by mass loss which compromise gravimetry. Dielectric measurements remained sensitive to moisture despite significant mass loss, which typically distorts the weight gain process complicating the commonly adopted gravimetric methodology. Real-time dielectric measurements were obtained from FRP specimens continuously immersed in water and without making use of any additional sensing elements. The novel approach adopted is of high commercial impact as moisture uptake control is recognized as a significant problem by industry.
Original languageEnglish
Pages (from-to)108-117
Number of pages10
JournalComposites Part A - Applied Science and Manufacturing
Early online date21 Nov 2017
Publication statusPublished - 28 Feb 2018


  • Dielectric changes
  • Glass fibre reinforced polymer
  • Impedance spectroscopy
  • Moisture uptake

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials


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