Effect of restraint on the shrinkage of masonry mortars

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AuthorSearch for:
Journal titleMaterials Research and Standards
Pages1316; # of pages: 4
Subjectmortar; shrinkage; constraints; forces (mechanics); loads; Mortar; Masonry
AbstractWhen restraining pressure was applied to mortar bars that shrank because their condition of storage was changed from 100 to 50 per cent RH, the shrinkage was less than that of unrestrained bars of the same composition. This inhibition of the shrinkage of mortar (and also of its expansion, as demonstrated in a previous study) is probably an important factor in the performance of masonry, since mortar in service in a wall is restrained by its bond to the masonry units and by structural loads on the wall. The dimensional changes of mortar in masonry will therefore be less than those of unrestrained mortar. The effect of restraint on shrinkage varied, depending on the composition. For three cement:lime:sand mortars, the effect was most pronounced with the lowest-strength mortar, and for these mortars it appeared that the influence of restraint on shrinkage may depend on the strength of the mortar. The shrinkage of bars of a masonry cement mortar was much reduced when restraint was applied. The behavior of the restrained bars of this mortar was unusual in that the restrained bars shrank and then expanded slightly. Tests with bars of 1:2:9 cement: lime:sand mortar indicated that as the restraining force was increased the shrinkage decreased.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedNo
NRC number8939
NPARC number20374730
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Record identifierf96f5430-ef20-4ee8-9135-f5cec4aa10f2
Record created2012-07-23
Record modified2016-05-09
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