Effect of Powdered Minerals and Fine Aggregate on the Drying Shrinkage of Portland Cement Paste

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Title: Effect of Powdered Minerals and Fine Aggregate on the Drying Shrinkage of Portland Cement Paste

Author(s): Kenneth M. Alexander and John Wardlaw

Publication: Journal Proceedings

Volume: 55

Issue: 6

Appears on pages(s): 1303-1316

Keywords: no keywords

Date: 6/1/1959

Abstract:
The extent to which fine aggregate and powdered minerals of cement fineness affect the drying shrinkage of portland cement paste was studied under a wide range of conditions. The water and powdered admixture contents of the paste were varied both separately and simultaneously, and the effect of gradually increasing the size of the powdered mineral grains until the admixture became an aggregate was studied. Results show that if the portland cement in a paste is partially replaced by powdered basalt, of cement fineness, and at a constant water-(cement -/-admixture) ratio, the effect on drying shrinkage represents a balance between the individual contributions arising from the simultaneous changes in the water-cement and admixture-cement ratios. An equation is given which relates both shrinkage and strength changes to changes in the water and admixture contents. When the effect of aggregate on drying shrinkage is considered in terms of the elastic constants of the embedded particle and the surrounding medium, some distinction should be made between the restraint imposed by rock particles small enough to fit between individual clinker grains, and that imposed by the same volume of rock in the form of grains or pebbles large enough to displace whole zones of clinker grains.