Freezing and Thawing Resistance of Concrete With Excessive Bleeding and Its Improvement

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Title: Freezing and Thawing Resistance of Concrete With Excessive Bleeding and Its Improvement

Author(s): M. Shoya, S. Nagataki, F. Tomosawa, S. Sugita and Y. Tsukinaga

Publication: Special Publication

Volume: 170

Issue:

Appears on pages(s): 879-898

Keywords: Admixtures; air-entrainment; bleeding (concrete); copper; fine aggregates; . freeze thaw durability; water-cement ratio.

Date: 7/1/1997

Abstract:
In recent years, especially in Japan, the research on the utilization of industrial by-products and the recycled aggregates has proceeded, with emphasis of recycling and use of resources. Among the industrial by-products applicable to concrete aggregates, non-ferrous metal slags for fine aggregates such as ferronickel slag and copper slag, are examined in this study. These slags are suitable for aggregates because they are almost inert both chemically and physically in concrete. Also, concretes with these slags generally show the same strength level as normal concrete. However, the more the volume fraction of slag fine aggregates, the greater the bleeding, usually because of the heavy specific weight and glass-like surface properties with irregular grain shape. It is possible that the excessive bleeding is likely to affect the concrete quality, such as aggravating frost susceptibility. In this paper, freezing and thawing resistance of concretes, with several kinds of slag fine aggregates, are investigated. The durability factor of concrete according to ASTM C 666A, decreased with increased bleeding amount, and the severe bleeding in excess of 5 I/ m 2 aggressively impaired the frost resistance of air-entrained concrete when the water to cement ratio and the volume fraction of slag in fine aggregates exceeded 60% and 50%, respectively. The decreased freezing and thawing resistance could be attributed to the internal defects originated by the up flow of bleeding water, measurement of the air void system, etc. It is also shown that the addition of a chemical admixture compound with cellulose ether and a powder-like material, such as the lime stone powder, are highly effective to improve not only the bleeding but also the freezing and thawing resistance of concrete.