Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/197366

Title

Mechanism of early age shrinkage of concretes

Author(s)

Aly, Tarek;  Sanjayan, J. G.

Abstract

Moist curing improves the properties of concrete. However, shrinkages at early ages are found to increase with increased curing. The reason for this phenomenon is studied with four binders and two types of curing. The binders are comprised of Portland cement/slag blends with 0, 35, 50 and 65% of slag. Initial moist curing times of 1 and 7 days were studied. The samples were then exposed to standard drying conditions (23° and 50% RH). During drying, the moisture losses in 7-day cured concretes were about 50% less than in 1-day cured concretes; however, the early age shrinkages were significantly higher in 7-day cured concrete. Pore size distribution tests and analyses showed that the pore radius where meniscus forms during drying is smaller in 7-day cured concrete due to finer pores, as compared to 1-day cured concrete. Further, good correlation can be seen between the meniscus radius and shrinkage, regardless of the binder and curing types. This provides the explanation for the increased early age shrinkage with increased curing. Further, this study demonstrates that the capillary tensile force is the governing mechanism for early age shrinkage.

Publication type

Journal article

Source

Materials and Structures, Vol. 42, no. 4 (May 2009), pp. 461-468

Publication year

2009

FOR Code(s)

0905 Civil Engineering

Keyword(s)

Binders;  Concretes;  Cured concretes;  Curing;  Dewatering;  Drying;  Drying conditions;  Early age;  Good correlations;  Moist curing;  Moisture;  Moisture loss;  Pore radius;  Pore size;  Pore size distribution;  Shrinkage;  Size distribution;  Slags;  Tensile forces;  Tests and analysis

Publisher

Springer

ISSN

1359-5997

Publisher URL

http://dx.doi.org/10.1617/s11527-008-9394-6

Copyright

Copyright © 2008 RILEM.

Peer reviewed