Effect of Silica Fume, Fly Ash and Water-to-Binder Ratio on Bond Strength of Underwater, Self-Consolidating Concrete

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Title: Effect of Silica Fume, Fly Ash and Water-to-Binder Ratio on Bond Strength of Underwater, Self-Consolidating Concrete

Author(s): Mohammed Sonebibond water-to-binder ratio

Publication: Special Publication

Volume: 199

Issue:

Appears on pages(s): 595-610

Keywords: strength; fly ash; silica fume; underwater concrete;

Date: 6/1/2001

Abstract:
Good adhesion of a repair material to concrete is of vital importance in the application and performance of underwater concrete repair. This paper reviews techniques and results of bond strength test methods: compressive slant-shear test and tensile bond (load-point) test. The objective of this paper is to evaluate the effects of variation in water-to-binder ratio and silica fume and fly ash replacements on bond strength of underwater concrete repairs. The mixtures were proportioned with a Canadian Type 10 cement and two other binders, one with 10% silica fume, and secondly a ternary cement containing 6% silica fume and 20% Class F fly ash replacements. The water-to-binder ratios tested were 0.41 and 0.47. The mixtures were cast in water, on slabs placed in the bottom of forms, in blocks measuring 0.50 x 0.45 x 1 m with the free fall height in water 0.35 m. Cores were obtained from experimental blocks cast in water to evaluate bond strength test between old and new concretes by tensile load-point. The slant-shear adhesion was determined by casting cylinders above water with consolidation, and in water without consolidation. The samples were composed of old concrete cast in air (sawed and smooth surface) with new concrete above. The incorporation of 10% of silica fume, or 20% of fly ash and 6% of silica fume and the reductions of water-to-binder ratio from 0.47 to 0.41 resulted in significant increases in bond strength.