A preliminary study of the influence of ions in the pore solution of hardened cement pastes on the porosity determination by low temperature calorimetry

Min Wu, Björn Johannesson, Mette Geiker

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Thermodynamic modeling was used to predict the ionic concentrations in the pore solution of cement pastes at different temperatures during a freezing and melting measurement in low temperature calorimetry (LTC) studies. By using the predicted ionic concentrations, the temperature depressions caused by the ions presented in the pore solution were determined. The influence of the freezing/melting point depression caused by the ions on the determined pore size distribution by LTC was demonstrated. Thermodynamic modeling using the program PHREEQC was performed on the cylinder and powder samples of cement pastes prepared by two types of cements, i.e., CEM 132.5 R and CEM III/B 42.5 N. Using the modeled ionic concentrations, the calculated differential pore size distributions for the studied samples with and without considering the temperature depression caused by the ions in the pore solution were compared. The results indicate that for the studied cement paste samples, the influence of the temperature depression caused by the presence of the ions in the pore solution on the determination of the pore size distribution by LTC is limited. (C) 2014 Elsevier B.V. All rights reserved.
Original languageEnglish
JournalThermochimica Acta
Volume589
Pages (from-to)215-225
Number of pages11
ISSN0040-6031
DOIs
Publication statusPublished - 2014

Keywords

  • Cement paste
  • Low temperature calorimetry
  • PHREEQC
  • Ionic strength
  • Pore size distribution
  • Thermoporometry

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