Phase transitions of adsorbates. IV. Mechanism of frost action in hardened cement paste

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TypeArticle
Journal titleJournal of the American Ceramic Society
ISSN0002-7820
Volume55
Issue1
Pages3842; # of pages: 5
Subjectphase transformations; cement; concrete (materials); frost; porosity; Concrete; transformation de phase; ciment; béton (matériau); gel (froid); porosité
AbstractThe dimensional changes and the thermograms of cement specimens were determined during temperature cycles (+5 degrees to -60 degrees C, 0.33 degrees C/min). In each case, freezing processes at -8 degrees and -40 degrees C and melting processes at -11 degrees and 0 degrees C were observed. The results could be explained by a theory previously developed for the porous-glass-water system. At the higher temperature, freezing occurs on the outer surface of the specimen; at the lower temperature, it occurs in the pores after redistribution of the water. Because water does not freeze in pores filled on adsorption, it migrates out of these pores when the relative humidity (expressed in terms of the vapor pressure of undercooled water), unavoidably decreases on cooling. Expansion is deleterious when the water content of the paste is significantly greater than the equilibrium value at the prevailing relative humidity. The effects of the water/cement ratio, degree of saturation, air entrainment, sample dimensions, and cooling rate were consistent with the theory.
Publication date
LanguageEnglish
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedNo
IdentifierDBR-RP-499
NRC number12220
2625
NPARC number20374780
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Record identifier83ae720e-10ff-41c5-ab26-8f76ce97dace
Record created2012-07-23
Record modified2016-05-09
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