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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Effect of Silica Fume and Fly Ash Replacement on Stability and Strength of Fluid Concrete Containing Anti-Washout Admixture
Author(s): K. H. Khayat, M. El Gattioui and C. Nmai
Publication: Special Publication
Appears on pages(s): 695-718
Keywords: Admixtures; bleeding (concrete); fly ash; segregation; settlement
(structural) silica fume; stability; strength; time of setting
Abstract:Anti-washout admixtures are used to enhance stability of cement-based systems, such as in the case of concrete intended for underwater repair of marine structures, self-leveling and segregation-free concrete for above-water placement, and for shotcrete. Mixtures modified with an anti-washout admixture can also incorporate silica fume or fly ash to enhance fresh and hardened properties. Anti-washout admixtures are relatively new, and there is a lack of systematic data comparing the efficiency, advantages, and limitations of using them in concrete, especially in silica fume or fly ash concrete. A laboratory investigation was undertaken to evaluate the effect of cementitious material combinations on fresh and hardened properties of fluid concrete made with three commonly used anti-washout admixtures. Each anti-washout admixture was used at two concentrations corresponding to relatively low and medium dosages that are typically used in concrete. The anti-washout admixtures included a powder-based product, a liquid-based cellulosic material, and a liquid-based microbial polysaccharide. The mixtures were prepared with 100% of a Type 10 cement, a blended silica fume ‘cement containing 8% silica fume, as well as a Class F fly ash used at 20% replacement. All mixtures were made with a 0.41 water-to-cementitious materials ratio and had initial slump values of 230 + 5 mm (9.1 + 0.2 in.). The influence of fly ash and silica fume incorporation on slump retention, washout resistance, bleeding, segregation, surface settlement, setting time, compressive and splitting-tensile strength developments was evaluated for the fluid mixtures. The paper summarizes the results of the experimental study that involved the comparison of data obtained from 21 concrete mixtures.
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