ON THE USE OF DIELECTRIC METHODS FOR RAPID MEASUREMENT OF CAPILLARY POROSITY IN SATURATED CEMENT PASTES

An alternative method, in which the content of pore water might be measured selectively without removing it from the saturated paste specimen, is suggested for the determination of porosity of cement pastes. The method involves the determination of dielectric data, capacitivity and relaxation conductivity, at a sufficiently high frequency. The theoretical background and experimental methods are described, and the applicablity to porosity determination of the particular method used, is tested on various materials. The main conclusion drawn from these studies is that the relationship between dielectric material data and porosity is far from unique or unambiguous. With the experimental methods of examination available, different types of substrate materials give widely differing relationships, and the tentative theoretical analysis has revealed a number of unknown or uncertain factors of influence. Among these, the distribution of pore size within the total porosity seems to be very important. A strong and variable contribution of ionic conductivity to the relaxation conductivity values measured at 36 MHz makes the use of the relationship, relaxation conductivity times capillary porosity, very uncertain as a method for capillary measurements. However, the capacitivity (dielectric constant) does not seem to be very much influenced by the presence of conducting ions, and it might perhaps be possible to apply the resonance method, as described, by calibrating out a set of average curves for cement materials of different porosities but equal degrees of hydration.

  • Supplemental Notes:
    • Paper presented at the RILEM/IUPAC Symposium, Prague, Sept. 18-21, 1973.
  • Corporate Authors:

    Cement och Betonginstitut

    Drottning Kristinas Vaeg 26
    Stockholm 70,   Sweden 
  • Authors:
    • Grudemo, A
  • Publication Date: 1975

Media Info

  • Features: Figures;
  • Pagination: 18 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00125449
  • Record Type: Publication
  • Report/Paper Numbers: 10:75
  • Files: TRIS
  • Created Date: Nov 5 1975 12:00AM