Permeability and Corrosion Resisting Characteristics of Fly Ash Concrete in Arabian Gulf Countries

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Title: Permeability and Corrosion Resisting Characteristics of Fly Ash Concrete in Arabian Gulf Countries

Author(s): Omar Saeed Baghabra Al-Amoudi

Publication: Special Publication

Volume: 114

Issue:

Appears on pages(s): 295-314

Keywords: aggregates; corrosion resistance; fly ash; permeability; porosity; reinforcing steels; tests; water-cement ratio; Materials Research

Date: 5/1/1989

Abstract:
Paper reports results of an investigation conducted to evaluate permeability, porosity, and the corrosion-resisting characteristics of fly ash concrete made with finely graded beach/dune sand and crushed limestone (typical aggregates used in the Arabian Gulf countries). The experimental program was designed to include concretes made with water-cement ratios in the range of 0.35 to 0.55. The effect of fly ash addition on water permeability, porosity, and pulse velocity was studied over a period of one year. Accelerated corrosion tests were carried out in the laboratory for a period of about 4 years to study the corrosion-resisting characteristics of these concrete mixes. Specimens were located in the exposure site to evaluate the effect of salt contamination on the corrosion of reinforcing bars in fly ash concrete. Time to cracking, weight loss of reinforcing bars, and pH measurements were also carried out on these specimens. Results show that fly ash incorporation in concrete improves its general quality. Fly ash concretes show significantly better performance than plain cement concrete mixes in terms of resistance against reinforcing bar corrosion. Also, fly ash concrete specimens contaminated with slats do not show a noticeable aggravation in the reinforcing bar corrosion process for 20 percent replacement and for a 9 month exposure period. Reaction between fly ash and calcium hydroxide does not reduce the pH value below the pH of pure saturated Ca(OH)2 solution (12.5), even after partial consumption of the calcium hydroxide by fly ash.