Interfacial transition zone characterization of portland cement mortars containing relatively high dosages of polynaphthalene sulfonate superplasticizers

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TypeArticle
Journal titleConcrete Science and Engineering
ISSN1295-2826
Volume2
IssueSeptember
Pages150157; # of pages: 8
Subjecttransition zone, cement, superplasticizers; Mortar; Admixtures
AbstractThe microstructure and interfacial transition zone characteristics of Portland cement mortars prepared with a polynaphthalene sulfate (PNS) superplasticizer at relatively high dosages (0.8%, 1.5% by mass of cement) and varying sand-to-cement ratios (0.5, 1.0, 1.5) were investigated, using AC impedance spectroscopy, mercury intrusion porosimetry, helium pycnometry and two electrical conductance models employing the interfacial excess conductance concept and Bruggeman's asymmetrical effective medium theories. The specimens containing superplasticizer exhibited higher electrical resistance, lower overall porosity and smaller interfacial excess conductance values compared to the corresponding control mortars. Experimental values of sm/sp, the relative conductivity (i.e. the conductivity ratio of mortar and paste) of mortars, are compared with the theoretical curve predicted by the Bruggeman's asymmetrical effective medium theory. All the experimental data falls above the theoretical line, indicating that as a whole the interfacial transition zone effect on electrical resistivity was to reduce resistivity. All the data points for the mortars with the PNS superplasticizer fall below the curves of plain mortars at 1 day and beyond, indicating that the superplasticizer had favorably modified the interfacial transition zone microstructure. The superplasticizer effect contributed to a reduction of electrical conductance of the system, compared to the system without PNS. The addition of large amounts of the PNS superplasticizer did not appear to have negative effects on the transition zone microstructure of the mortars studied.
Publication date
LanguageEnglish
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number40302
9215
NPARC number20331326
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Record identifierc3a21866-2594-4c58-a277-685dd481468b
Record created2012-07-18
Record modified2016-05-09
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