Intrinsic Permeability of Fly Ash Concrete

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Title: Intrinsic Permeability of Fly Ash Concrete

Author(s): C. Y. Lee, M. J. McCarthy and R. K. Dhir

Publication: Special Publication

Volume: 170

Issue:

Appears on pages(s): 247-266

Keywords: Concretes; curing; durability; fly ash; permeability; strength.

Date: 7/1/1997

Abstract:
In the study reported in this paper. the permeability of normal portland cement (PC) and fly ash (FA) concretes containing 15%. 30% and 45% FA were investigated. These were compared on an equal 28 day strength basis (and therefore had increasing binder contents and reducing W/B with increasing FA content at a given design strength). A further series of FA concretes (45%), combined with two active early strength cements to overcoming low early strength were also considered. The results followed expected behaviour in terms of strength/permeability relationships. It was also found that the permeabilities of FA concretes were lower than those of PC concrete. with greater differences at increasing FA level. The permeability of all concretes cured in water was significantly lower than those of concrete cured in air, but the differences reduced with increasing FA level. suggesting that this concrete may be less sensitive to limited moist curing. Long-term curing in water lead to reductions in permeability for all concretes, while that in ai r generally lead to slight increases. Comparison between pemeabilities of high FA content concretes indicated similar performance between these. although the exact ranking varied slightly depending on the curin g conditions. It was found that the performance of high FA concrete was better than PC concrete under a wide range of temperature and moisture curing conditions, but this may be reversed under low temperature, cold curing conditions. A ranking of the FA concretes to illustrate their potential durability is provided.