Effect of phlogopite mica on alkali-aggregate expnsion in concrete

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DOIResolve DOI: http://doi.org/10.1016/0008-8846(80)90007-1
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Journal titleCement and Concrete Research
IssueNovember 6
Pages789797; # of pages: 9
Subjectconcrete admixtures; alkalinity; mica; tensile strength; expansion; Concrete
AbstractThe tensile strength of concrete is increased by the addition of high aspect-ratio mica reinforcement. Phlogopite mica contains about 10% K[2]O; soluble K+ would contribute to the alkalinity of the pore solution in concrete enhancing its potential expansivity if it is made with alkali-expansive aggregate. Electron microprobe analysis confirms that the solubility of K+ from phlogopite in cement paste, about 0.09% is the same as in mixed calcium- sodium-hydroxide solutions. The addition of 1.5% by volume of phlogopite to concrete prisms made with alkali-carbonate expansive aggregates caused a small increase in the rate of expansion of prisms made with both high and low alkali cement. It is concluded that the addition of small quantities of phlogopite as a reinforcement in concrete is not a cause for concern, although caution should be exercised in adding larger volumes to concrete made with potentially alkali-expansive aggregate.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number18670
NPARC number20375956
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Record identifier4e8270af-a191-46f0-b590-8e62340840ae
Record created2012-07-23
Record modified2016-05-09
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