Overview of Fly Ash and Silica Fume Concretes: The Need for Rational Curing Standards


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Title: Overview of Fly Ash and Silica Fume Concretes: The Need for Rational Curing Standards

Author(s): M. E. Ayers and M. S. Khan

Publication: Special Publication

Volume: 144


Appears on pages(s): 605-622

Keywords: air entrainment; bleeding (concrete); curing;, durability; fly ash; heat of hydration; permeability; plastic shrinkage; segregation; silica fume; strength; workability; Materials Research

Date: 3/1/1994

Developments in the use of fly ash and silica fume in portland cement concrete are critically reviewed. Concrete properties, both in the fresh and hardened states, that are influenced by the addition of fly ash and silica fume are discussed. The effects on workability, segregation, bleeding, air entrainment, heat of hydration, and plastic shrinkage cracking are reviewed relative to fresh concrete. The influence on strength, permeability, drying shrinkage, creep, steel-to-concrete bond, alkali-silica reactivity, resistance to reinforcing steel corrosion, and resistance to sulfate attack are documented for hardened concrete. The curing requirement of fly ash and silica fume concrete is identified as one of the important areas that needs further investigation to utilize the full potential of these concretes. The literature contains a reasonable amount of data concerning the curing requirement of fly ash concretes. However, very limited data on the curing requirements of silica fume concrete are available. A significant amount of confusion exists in the construction industry regarding the curing of silica fume concrete. In the absence of adequate specifications, overcuring of silica fume concrete is the general practice. A brief review of the available literature concerning the curing requirements of fly ash and silica fume concretes is presented.